Transition-metal doped topological insulators have been widely explored since the observation of quantum anomalous Hall effect (QAHE). Subsequently, the magnetic (Pb,Sn)(Te,Se) was predicted to possibly possess a high-temperature QAHE state. However, the fundamental understanding of Cr-doping-induced ferromagnetism in this system remains unclear. Here, we report the stable ferromagnetism in the high-crystalline Cr-doped SnTe films. Upon Cr doping, the magnetoconductance unveils a crossover from weak antilocalization to weak localization. Further increasing the Cr concentration to Cr0.17Sn0.83Te introduces a strong ferromagnetism with a Curie temperature of ~140 K. We detected a sizable spin moment ms = 2.28 ± 0.23 μB/Cr and a suppressed orbital moment ml = 0.02 μB/Cr. Cr dopants prefer to substitute the Sn sites and behave as divalent cations, as indicated by the experimental results and density function theory calculations. The controllable growth of magnetic SnTe thin films provides enlightenment towards the high-temperature QAHE in magnetic TCIs for the desired dissipationless transport in electronics.
{"title":"Cr doping-induced ferromagnetism in SnTe thin films","authors":"Shanshan Liu, Enze Zhang, Zihan Li, Xiaoqian Zhang, Wenqing Liu, Awadhesh Narayan, Zhi-Gang Chen, Jin Zou, Faxian Xiu","doi":"10.1038/s41535-024-00667-x","DOIUrl":"https://doi.org/10.1038/s41535-024-00667-x","url":null,"abstract":"<p>Transition-metal doped topological insulators have been widely explored since the observation of quantum anomalous Hall effect (QAHE). Subsequently, the magnetic (Pb,Sn)(Te,Se) was predicted to possibly possess a high-temperature QAHE state. However, the fundamental understanding of Cr-doping-induced ferromagnetism in this system remains unclear. Here, we report the stable ferromagnetism in the high-crystalline Cr-doped SnTe films. Upon Cr doping, the magnetoconductance unveils a crossover from weak antilocalization to weak localization. Further increasing the Cr concentration to Cr<sub>0.17</sub>Sn<sub>0.83</sub>Te introduces a strong ferromagnetism with a Curie temperature of ~140 K. We detected a sizable spin moment <i>m</i><sub>s</sub> = 2.28 ± 0.23 <i>μ</i><sub>B</sub>/Cr and a suppressed orbital moment <i>m</i><sub>l</sub> = 0.02 <i>μ</i><sub>B</sub>/Cr. Cr dopants prefer to substitute the Sn sites and behave as divalent cations, as indicated by the experimental results and density function theory calculations. The controllable growth of magnetic SnTe thin films provides enlightenment towards the high-temperature QAHE in magnetic TCIs for the desired dissipationless transport in electronics.</p>","PeriodicalId":19283,"journal":{"name":"npj Quantum Materials","volume":"170 1","pages":""},"PeriodicalIF":5.7,"publicationDate":"2024-07-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141732680","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Superconductivity in quasicrystals poses a new challenge in condensed matter physics. We measured the resistance and ac magnetic susceptibility of a Ta1.6Te dodecagonal quasicrystal, which is superconducting below Tc ~ 1 K. We show that the upper critical field increases linearly with a large slope of − 4.4 T/K with decreasing temperature down to 0.04 K, with no tendency to level off. The extrapolated zero-temperature critical field exceeds the Pauli limit by a factor of 2.3. We also observed flux-flow resistance with thermally activated behavior and an irreversibility field that is distinct from the upper critical field. We discuss these peculiarities in terms of the nonuniform superconducting gap and spin-orbit interaction in quasicrystal structures.
{"title":"Anomalous upper critical field in the quasicrystal superconductor Ta1.6Te","authors":"Taichi Terashima, Yuki Tokumoto, Kotaro Hamano, Takako Konoike, Naoki Kikugawa, Keiichi Edagawa","doi":"10.1038/s41535-024-00669-9","DOIUrl":"https://doi.org/10.1038/s41535-024-00669-9","url":null,"abstract":"<p>Superconductivity in quasicrystals poses a new challenge in condensed matter physics. We measured the resistance and ac magnetic susceptibility of a Ta<sub>1.6</sub>Te dodecagonal quasicrystal, which is superconducting below <i>T</i><sub><i>c</i></sub> ~ 1 K. We show that the upper critical field increases linearly with a large slope of − 4.4 T/K with decreasing temperature down to 0.04 K, with no tendency to level off. The extrapolated zero-temperature critical field exceeds the Pauli limit by a factor of 2.3. We also observed flux-flow resistance with thermally activated behavior and an irreversibility field that is distinct from the upper critical field. We discuss these peculiarities in terms of the nonuniform superconducting gap and spin-orbit interaction in quasicrystal structures.</p>","PeriodicalId":19283,"journal":{"name":"npj Quantum Materials","volume":"6 1","pages":""},"PeriodicalIF":5.7,"publicationDate":"2024-07-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141730558","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-07-20DOI: 10.1038/s41535-024-00666-y
Jonghyeon Kim, Saikat Banerjee, Junghyun Kim, Minseong Lee, Suhan Son, Jangwon Kim, Taek Sun Jung, Kyung Ik Sim, Je-Geun Park, Jae Hoon Kim
Chromium tri-iodide (CrI3) is a prototypical ferromagnetic van der Waals insulator with its genuinely two-dimensional (2D) long-range magnetic order below 45 K demonstrated recently. The underlying magnetic anisotropy has not been completely understood while both the Dzyaloshinskii-Moriya (DM) interaction and the Kitaev(-Gamma) type interaction have been considered as the relevant magnetic Hamiltonian. In addition, the relation between the crystal structure and the magnetic order needs to be further elucidated concerning their possible coupling in few-layer samples and in the topmost surface layers of bulk samples. Here, we investigate these issues via temperature- and magnetic field-dependent terahertz spectroscopy on bulk CrI3 single crystals, focusing on the dynamics of ferromagnetic resonances (FMRs) and optical phonons in the terahertz (THz) region from 4 to 120 cm−1 (from 0.5 to 15 meV). We narrow down the possible ranges of the interaction parameters such as the off-diagonal symmetric terms and the single-ion anisotropy. The accurate values of these parameters significantly constrain the magnitude of possible Kitaev(-Gamma) exchange interaction and the topological magnon gap. Moreover, the structure-magnetism relationship was critically analyzed based on the temperature- and field-dependences of two ({{rm{E}}}_{{rm{u}}}) in-plane optical phonon modes, which shows that the commonly believed structural phase diagram of CrI3, derived from surface-preferential data, has to be seriously modified.
{"title":"Spin and lattice dynamics of the two-dimensional van der Waals ferromagnet CrI3","authors":"Jonghyeon Kim, Saikat Banerjee, Junghyun Kim, Minseong Lee, Suhan Son, Jangwon Kim, Taek Sun Jung, Kyung Ik Sim, Je-Geun Park, Jae Hoon Kim","doi":"10.1038/s41535-024-00666-y","DOIUrl":"https://doi.org/10.1038/s41535-024-00666-y","url":null,"abstract":"<p>Chromium tri-iodide (CrI<sub>3</sub>) is a prototypical ferromagnetic van der Waals insulator with its genuinely two-dimensional (2D) long-range magnetic order below 45 K demonstrated recently. The underlying magnetic anisotropy has not been completely understood while both the Dzyaloshinskii-Moriya (DM) interaction and the Kitaev<span>(-Gamma)</span> type interaction have been considered as the relevant magnetic Hamiltonian. In addition, the relation between the crystal structure and the magnetic order needs to be further elucidated concerning their possible coupling in few-layer samples and in the topmost surface layers of bulk samples. Here, we investigate these issues via temperature- and magnetic field-dependent terahertz spectroscopy on bulk CrI<sub>3</sub> single crystals, focusing on the dynamics of ferromagnetic resonances (FMRs) and optical phonons in the terahertz (THz) region from 4 to 120 cm<sup>−1</sup> (from 0.5 to 15 meV). We narrow down the possible ranges of the interaction parameters such as the off-diagonal symmetric terms and the single-ion anisotropy. The accurate values of these parameters significantly constrain the magnitude of possible Kitaev<span>(-Gamma)</span> exchange interaction and the topological magnon gap. Moreover, the structure-magnetism relationship was critically analyzed based on the temperature- and field-dependences of two <span>({{rm{E}}}_{{rm{u}}})</span> in-plane optical phonon modes, which shows that the commonly believed structural phase diagram of CrI<sub>3</sub>, derived from surface-preferential data, has to be seriously modified.</p>","PeriodicalId":19283,"journal":{"name":"npj Quantum Materials","volume":"27 1","pages":""},"PeriodicalIF":5.7,"publicationDate":"2024-07-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141730560","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-07-11DOI: 10.1038/s41535-024-00664-0
Hung-Hsiang Yang, Louise Desplat, Volodymyr P. Kravchuk, Marie Hervé, Timofey Balashov, Simon Gerber, Markus Garst, Bertrand Dupé, Wulf Wulfhekel
The nanoscopic magnetic texture forming in a monolayer of iron on the (111) surface of iridium, Fe/Ir(111), is spatially modulated and uniaxially incommensurate with respect to the crystallographic periodicities. As a consequence, a low-energy magnetic excitation is expected that corresponds to the sliding of the texture along the incommensurate direction, i.e., a phason mode, which we explicitly confirm with atomistic spin simulations. Using scanning tunneling microscopy (STM), we succeed to observe this phason mode experimentally. It can be excited by the STM tip, which leads to a random telegraph noise in the tunneling current that we attribute to the presence of two minima in the phason potential due to the presence of disorder in our sample. This provides the prospect of a floating phase in cleaner samples and, potentially, a commensurate-incommensurate transition as a function of external control parameters.
{"title":"Observation of the sliding phason mode of the incommensurate magnetic texture in Fe/Ir(111)","authors":"Hung-Hsiang Yang, Louise Desplat, Volodymyr P. Kravchuk, Marie Hervé, Timofey Balashov, Simon Gerber, Markus Garst, Bertrand Dupé, Wulf Wulfhekel","doi":"10.1038/s41535-024-00664-0","DOIUrl":"https://doi.org/10.1038/s41535-024-00664-0","url":null,"abstract":"<p>The nanoscopic magnetic texture forming in a monolayer of iron on the (111) surface of iridium, Fe/Ir(111), is spatially modulated and uniaxially incommensurate with respect to the crystallographic periodicities. As a consequence, a low-energy magnetic excitation is expected that corresponds to the sliding of the texture along the incommensurate direction, i.e., a phason mode, which we explicitly confirm with atomistic spin simulations. Using scanning tunneling microscopy (STM), we succeed to observe this phason mode experimentally. It can be excited by the STM tip, which leads to a random telegraph noise in the tunneling current that we attribute to the presence of two minima in the phason potential due to the presence of disorder in our sample. This provides the prospect of a floating phase in cleaner samples and, potentially, a commensurate-incommensurate transition as a function of external control parameters.</p>","PeriodicalId":19283,"journal":{"name":"npj Quantum Materials","volume":"78 1","pages":""},"PeriodicalIF":5.7,"publicationDate":"2024-07-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141584527","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-07-09DOI: 10.1038/s41535-024-00661-3
Jonas B. Profe, Sophie Beck, Dante M. Kennes, Antoine Georges, Olivier Gingras
The pairing symmetry of Sr2RuO4 is a long-standing fundamental question in the physics of superconducting materials with strong electronic correlations. We use the functional renormalization group to investigate the behavior of superconductivity under uniaxial strain in a two-dimensional realistic model of Sr2RuO4 obtained with density functional theory and incorporating the effect of spin-orbit coupling. We find a dominant ({d}_{{{{{rm{x}}}}}^{2}-{{{{rm{y}}}}}^{2}}) superconductor mostly hosted by the dxy-orbital, with no other closely competing superconducting state. Within this framework, we reproduce the experimentally observed enhancement of the critical temperature under strain and propose a simple mechanism driven by the density of states to explain our findings. We also investigate the competition between superconductivity and spin-density wave ordering as a function of interaction strength. By comparing theory and experiment, we discuss constraints on a possible degenerate partner of the ({d}_{{{{{rm{x}}}}}^{2}-{{{{rm{y}}}}}^{2}}) superconducting state.
{"title":"Competition between d-wave superconductivity and magnetism in uniaxially strained Sr2RuO4","authors":"Jonas B. Profe, Sophie Beck, Dante M. Kennes, Antoine Georges, Olivier Gingras","doi":"10.1038/s41535-024-00661-3","DOIUrl":"https://doi.org/10.1038/s41535-024-00661-3","url":null,"abstract":"<p>The pairing symmetry of Sr<sub>2</sub>RuO<sub>4</sub> is a long-standing fundamental question in the physics of superconducting materials with strong electronic correlations. We use the functional renormalization group to investigate the behavior of superconductivity under uniaxial strain in a two-dimensional realistic model of Sr<sub>2</sub>RuO<sub>4</sub> obtained with density functional theory and incorporating the effect of spin-orbit coupling. We find a dominant <span>({d}_{{{{{rm{x}}}}}^{2}-{{{{rm{y}}}}}^{2}})</span> superconductor mostly hosted by the <i>d</i><sub>xy</sub>-orbital, with no other closely competing superconducting state. Within this framework, we reproduce the experimentally observed enhancement of the critical temperature under strain and propose a simple mechanism driven by the density of states to explain our findings. We also investigate the competition between superconductivity and spin-density wave ordering as a function of interaction strength. By comparing theory and experiment, we discuss constraints on a possible degenerate partner of the <span>({d}_{{{{{rm{x}}}}}^{2}-{{{{rm{y}}}}}^{2}})</span> superconducting state.</p>","PeriodicalId":19283,"journal":{"name":"npj Quantum Materials","volume":"36 1","pages":""},"PeriodicalIF":5.7,"publicationDate":"2024-07-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141576274","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-07-08DOI: 10.1038/s41535-024-00663-1
Z. Zajicek, P. Reiss, D. Graf, J. C. A. Prentice, Y. Sadki, A. A. Haghighirad, A. I. Coldea
Superconductivity of iron chalocogenides is strongly enhanced under applied pressure yet its underlying pairing mechanism remains elusive. Here, we present a quantum oscillations study up to 45 T in the high-Tc phase of tetragonal FeSe0.82S0.18 up to 22 kbar. Under applied pressure, the quasi-two-dimensional multi-band Fermi surface expands and the effective masses remain large, whereas the superconductivity displays a threefold enhancement. Comparing with chemical pressure tuning of FeSe1−xSx, the Fermi surface expands in a similar manner but the effective masses and Tc are suppressed. These differences may be attributed to the changes in the density of states influenced by the chalcogen height, which could promote stronger spin fluctuations pairing under pressure. Furthermore, our study also reveals unusual scattering and broadening of superconducting transitions in the high-pressure phase, indicating the presence of a complex pairing mechanism.
{"title":"Unveiling the quasiparticle behaviour in the pressure-induced high-Tc phase of an iron-chalcogenide superconductor","authors":"Z. Zajicek, P. Reiss, D. Graf, J. C. A. Prentice, Y. Sadki, A. A. Haghighirad, A. I. Coldea","doi":"10.1038/s41535-024-00663-1","DOIUrl":"https://doi.org/10.1038/s41535-024-00663-1","url":null,"abstract":"<p>Superconductivity of iron chalocogenides is strongly enhanced under applied pressure yet its underlying pairing mechanism remains elusive. Here, we present a quantum oscillations study up to 45 T in the high-<i>T</i><sub>c</sub> phase of tetragonal FeSe<sub>0.82</sub>S<sub>0.18</sub> up to 22 kbar. Under applied pressure, the quasi-two-dimensional multi-band Fermi surface expands and the effective masses remain large, whereas the superconductivity displays a threefold enhancement. Comparing with chemical pressure tuning of FeSe<sub>1−<i>x</i></sub>S<sub><i>x</i></sub>, the Fermi surface expands in a similar manner but the effective masses and <i>T</i><sub>c</sub> are suppressed. These differences may be attributed to the changes in the density of states influenced by the chalcogen height, which could promote stronger spin fluctuations pairing under pressure. Furthermore, our study also reveals unusual scattering and broadening of superconducting transitions in the high-pressure phase, indicating the presence of a complex pairing mechanism.</p>","PeriodicalId":19283,"journal":{"name":"npj Quantum Materials","volume":"13 1","pages":""},"PeriodicalIF":5.7,"publicationDate":"2024-07-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141561199","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-07-04DOI: 10.1038/s41535-024-00662-2
Kyoung-Min Kim, Suk Bum Chung
The concept of ferroelectricity is now often extended to include continuous inversion symmetry-breaking transitions in various metals and doped semiconductors. Paraelectric metals near ferroelectric quantum criticality, which we term ‘quantum paraelectric metals,’ possess soft transverse optical phonons which can have Rashba-type coupling to itinerant electrons in the presence of spin-orbit coupling. We find through the Kubo formula calculation that such Rashba electron-phonon coupling has a profound impact on electron spin transport. While the spin Hall effect arising from non-trivial electronic band structures has been studied extensively, we find here the presence of the Rashba electron-phonon coupling can give rise to spin current, including spin Hall current, in response to an inhomogeneous electric field even with a completely trivial band structure. Furthermore, this spin conductivity displays unconventional characteristics, such as quadrupolar symmetry associated with the wave vector of the electric field and a thermal activation behavior characterized by scaling laws dependent on the phonon frequency to temperature ratio. These findings shed light on exotic electronic transport phenomena originating from ferroelectric quantum criticality, highlighting the intricate interplay of charge and spin degrees of freedom.
{"title":"Phonon-mediated spin transport in quantum paraelectric metals","authors":"Kyoung-Min Kim, Suk Bum Chung","doi":"10.1038/s41535-024-00662-2","DOIUrl":"https://doi.org/10.1038/s41535-024-00662-2","url":null,"abstract":"<p>The concept of ferroelectricity is now often extended to include continuous inversion symmetry-breaking transitions in various metals and doped semiconductors. Paraelectric metals near ferroelectric quantum criticality, which we term ‘quantum paraelectric metals,’ possess soft transverse optical phonons which can have Rashba-type coupling to itinerant electrons in the presence of spin-orbit coupling. We find through the Kubo formula calculation that such Rashba electron-phonon coupling has a profound impact on electron spin transport. While the spin Hall effect arising from non-trivial electronic band structures has been studied extensively, we find here the presence of the Rashba electron-phonon coupling can give rise to spin current, including spin Hall current, in response to an inhomogeneous electric field even with a completely trivial band structure. Furthermore, this spin conductivity displays unconventional characteristics, such as quadrupolar symmetry associated with the wave vector of the electric field and a thermal activation behavior characterized by scaling laws dependent on the phonon frequency to temperature ratio. These findings shed light on exotic electronic transport phenomena originating from ferroelectric quantum criticality, highlighting the intricate interplay of charge and spin degrees of freedom.</p>","PeriodicalId":19283,"journal":{"name":"npj Quantum Materials","volume":"133 1","pages":""},"PeriodicalIF":5.7,"publicationDate":"2024-07-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141521458","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-06-14DOI: 10.1038/s41535-024-00655-1
Mengqi Zhao, Aitian Chen, Pei-Yuan Huang, Chen Liu, Laichuan Shen, Jiahao Liu, Le Zhao, Bin Fang, Wen-Cheng Yue, Dongxing Zheng, Ledong Wang, Hao Bai, Ka Shen, Yan Zhou, Shasha Wang, Enlong Liu, Shikun He, Yong-Lei Wang, Xixiang Zhang, Wanjun Jiang
Magnetic skyrmions are topological spin textures that are regarded as promising information carriers for next-generation spintronic memory and computing devices. For practical applications, their deterministic generation, manipulation, and efficient detection are the most critical aspects. Although the generation and manipulation of skyrmions have been extensively studied, efficient electrical detection of mobile skyrmions by using techniques that are compatible with modern magnetic memory technology, remains to be adequately addressed. Here, through integrating magnetic multilayers that host nanoscale skyrmions, together with the magnetic tunnel junctions (MTJ), we demonstrate the electrical detection of skyrmions by using the tunneling magnetoresistance (TMR) effect with a TMR ratio that reaches over 100% at room temperature. By building prototype three-terminal racetrack-like devices, we further show the electrical detection of mobile skyrmions by recording the time-dependent TMR ratios. Along with many recent developments, our results could advance the development of skyrmionic memory and logic devices.
{"title":"Electrical detection of mobile skyrmions with 100% tunneling magnetoresistance in a racetrack-like device","authors":"Mengqi Zhao, Aitian Chen, Pei-Yuan Huang, Chen Liu, Laichuan Shen, Jiahao Liu, Le Zhao, Bin Fang, Wen-Cheng Yue, Dongxing Zheng, Ledong Wang, Hao Bai, Ka Shen, Yan Zhou, Shasha Wang, Enlong Liu, Shikun He, Yong-Lei Wang, Xixiang Zhang, Wanjun Jiang","doi":"10.1038/s41535-024-00655-1","DOIUrl":"https://doi.org/10.1038/s41535-024-00655-1","url":null,"abstract":"<p>Magnetic skyrmions are topological spin textures that are regarded as promising information carriers for next-generation spintronic memory and computing devices. For practical applications, their deterministic generation, manipulation, and efficient detection are the most critical aspects. Although the generation and manipulation of skyrmions have been extensively studied, efficient electrical detection of mobile skyrmions by using techniques that are compatible with modern magnetic memory technology, remains to be adequately addressed. Here, through integrating magnetic multilayers that host nanoscale skyrmions, together with the magnetic tunnel junctions (MTJ), we demonstrate the electrical detection of skyrmions by using the tunneling magnetoresistance (TMR) effect with a TMR ratio that reaches over 100% at room temperature. By building prototype three-terminal racetrack-like devices, we further show the electrical detection of mobile skyrmions by recording the time-dependent TMR ratios. Along with many recent developments, our results could advance the development of skyrmionic memory and logic devices.</p>","PeriodicalId":19283,"journal":{"name":"npj Quantum Materials","volume":"1 1","pages":""},"PeriodicalIF":5.7,"publicationDate":"2024-06-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141319785","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-06-06DOI: 10.1038/s41535-024-00659-x
Fangze Liu, Cheng Peng, Edwin W. Huang, Brian Moritz, Chunjing Jia, Thomas P. Devereaux
We report a determinant quantum Monte Carlo study of a two-band model, inspired by infinite-layer nickelates, focusing on the influence of interlayer hybridization between (3{d}_{{x}^{2}-{y}^{2}}) orbitals derived from Ni (or Ni and O) in one layer and rare-earth (R) 5d orbitals in the other layer, hereafter the Ni and R layers, respectively. For a filling with one electron shared between the two layers on average, interlayer hybridization leads to “self-doped" holes in the Ni layer and the absence of antiferromagnetic ordering, but rather the appearance of spin-density and charge-density stripe-like states. As the interlayer hybridization increases, both the Ni and R layers develop antiferromagnetic correlations, even though either layer individually remains away from half-filling. For hybridization within an intermediate range, roughly comparable to the intralayer nearest-neighbor hopping tNi, the model develops signatures of Kondo-like physics.
我们报告了受无限层镍酸盐启发而对双带模型进行的行列式量子蒙特卡洛研究,重点研究了一层中来自镍(或镍和O)的(3{d}_{{x}^{2}-{y}^{2}})轨道与另一层中稀土(R)5d轨道之间的层间杂化的影响,以下分别称为镍层和R层。对于两层平均共用一个电子的填充物,层间杂化会导致镍层出现 "自掺杂 "空穴,并且没有反铁磁有序,而是出现自旋密度和电荷密度的条纹状状态。随着层间杂化程度的增加,镍层和 R 层都会出现反铁磁关联,即使其中任何一层仍然远离半填充。对于中间范围内的杂化(与层内近邻跳变 tNi 大致相当),模型出现了类似近藤物理的特征。
{"title":"Emergence of antiferromagnetic correlations and Kondolike features in a model for infinite layer nickelates","authors":"Fangze Liu, Cheng Peng, Edwin W. Huang, Brian Moritz, Chunjing Jia, Thomas P. Devereaux","doi":"10.1038/s41535-024-00659-x","DOIUrl":"https://doi.org/10.1038/s41535-024-00659-x","url":null,"abstract":"<p>We report a determinant quantum Monte Carlo study of a two-band model, inspired by infinite-layer nickelates, focusing on the influence of interlayer hybridization between <span>(3{d}_{{x}^{2}-{y}^{2}})</span> orbitals derived from Ni (or Ni and O) in one layer and rare-earth (<i>R</i>) 5<i>d</i> orbitals in the other layer, hereafter the Ni and <i>R</i> layers, respectively. For a filling with one electron shared between the two layers on average, interlayer hybridization leads to “self-doped\" holes in the Ni layer and the absence of antiferromagnetic ordering, but rather the appearance of spin-density and charge-density stripe-like states. As the interlayer hybridization increases, both the Ni and <i>R</i> layers develop antiferromagnetic correlations, even though either layer individually remains away from half-filling. For hybridization within an intermediate range, roughly comparable to the intralayer nearest-neighbor hopping <i>t</i><sub>Ni</sub>, the model develops signatures of Kondo-like physics.</p>","PeriodicalId":19283,"journal":{"name":"npj Quantum Materials","volume":"26 1","pages":""},"PeriodicalIF":5.7,"publicationDate":"2024-06-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141264897","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-06-06DOI: 10.1038/s41535-024-00650-6
Joseph A. M. Paddison, Hao Zhang, Jiaqiang Yan, Matthew J. Cliffe, Michael A. McGuire, Seung-Hwan Do, Shang Gao, Matthew B. Stone, David Dahlbom, Kipton Barros, Cristian D. Batista, Andrew D. Christianson
Magnetic materials with noncoplanar magnetic structures can show unusual physical properties driven by nontrivial topology. Topologically-active states are often multi-q structures, which are challenging to stabilize in models and to identify in materials. Here, we use inelastic neutron-scattering experiments to show that the insulating double perovskites Ba2YRuO6 and Ba2LuRuO6 host a noncoplanar 3-q structure on the face-centered cubic lattice. Quantitative analysis of our neutron-scattering data reveals that these 3-q states are stabilized by biquadratic interactions. Our study identifies double perovskites as a highly promising class of materials to realize topological magnetism, elucidates the stabilization mechanism of the 3-q state in these materials, and establishes neutron spectroscopy on powder samples as a valuable technique to distinguish multi-q from single-q states, facilitating the discovery of topologically-nontrivial magnetic materials.
{"title":"Cubic double perovskites host noncoplanar spin textures","authors":"Joseph A. M. Paddison, Hao Zhang, Jiaqiang Yan, Matthew J. Cliffe, Michael A. McGuire, Seung-Hwan Do, Shang Gao, Matthew B. Stone, David Dahlbom, Kipton Barros, Cristian D. Batista, Andrew D. Christianson","doi":"10.1038/s41535-024-00650-6","DOIUrl":"https://doi.org/10.1038/s41535-024-00650-6","url":null,"abstract":"<p>Magnetic materials with noncoplanar magnetic structures can show unusual physical properties driven by nontrivial topology. Topologically-active states are often multi-<b>q</b> structures, which are challenging to stabilize in models and to identify in materials. Here, we use inelastic neutron-scattering experiments to show that the insulating double perovskites Ba<sub>2</sub>YRuO<sub>6</sub> and Ba<sub>2</sub>LuRuO<sub>6</sub> host a noncoplanar 3-<b>q</b> structure on the face-centered cubic lattice. Quantitative analysis of our neutron-scattering data reveals that these 3-<b>q</b> states are stabilized by biquadratic interactions. Our study identifies double perovskites as a highly promising class of materials to realize topological magnetism, elucidates the stabilization mechanism of the 3-<b>q</b> state in these materials, and establishes neutron spectroscopy on powder samples as a valuable technique to distinguish multi-<b>q</b> from single-<b>q</b> states, facilitating the discovery of topologically-nontrivial magnetic materials.</p>","PeriodicalId":19283,"journal":{"name":"npj Quantum Materials","volume":"70 1","pages":""},"PeriodicalIF":5.7,"publicationDate":"2024-06-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141264803","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}