Pub Date : 2024-10-26DOI: 10.1038/s44306-024-00056-x
Po-Hao Chang, Igor I. Mazin
Magnetism in the Zintl compound Ba14MnBi11 is rather poorly understood. Experimental claims are largely inconsistent with ab initio calculations, much beyond typical errors of the latter. We revisit this old problem, assuming that the root of the problem may be in nonstoichiometry of existing samples. Our key finding is that the magnetic ground state is indeed very susceptible to charge doping (band filling). Calculations for stoichiometric Ba14MnBi11 give a rather stable ferromagnetic metallic state, in agreement with previous publications. However, by adding exactly one electron per Mn, the system becomes semiconducting as expected, and becomes weakly antiferromagnetic (AF). On the other hand, upon small amount of hole doping, the system transitions to a special type of AF state known as altermagnetism. Furthermore, hole and electron doping-induced phase transitions result from different underlying mechanisms, influencing different exchange pathways. We propose that the inconsistency between experiment and theory is not a failure of the latter, but results from a nontrivial ramification of nonstoichiometry. The possibility of doping-stabilized altermagnetism is exciting.
人们对 Zintl 化合物 Ba14MnBi11 的磁性了解甚少。实验结果在很大程度上与 ab initio 计算结果不一致，远远超出了后者的典型误差。我们重新审视了这个老问题，假设问题的根源可能在于现有样品的非化学计量。我们的主要发现是，磁基态确实非常容易受到电荷掺杂（带填充）的影响。通过计算化学计量 Ba14MnBi11，可以得到相当稳定的铁磁金属态，这与之前发表的文章一致。然而，当每锰恰好加入一个电子时，该体系就会如预期的那样成为半导体，并变成弱反铁磁性（AF）。另一方面，当掺入少量空穴时，体系会过渡到一种特殊的反铁磁性（AF）状态，即所谓的 "变磁"（altermagnetism）。此外，空穴掺杂和电子掺杂诱导的相变产生于不同的基本机制，影响着不同的交换途径。我们提出，实验与理论之间的不一致并不是理论的失败，而是由于非化学计量学的非微不足道的衍生物造成的。掺杂稳定变磁性的可能性令人兴奋。
{"title":"The mysterious magnetic ground state of Ba14MnBi11 is likely self-doped and altermagnetic","authors":"Po-Hao Chang, Igor I. Mazin","doi":"10.1038/s44306-024-00056-x","DOIUrl":"10.1038/s44306-024-00056-x","url":null,"abstract":"Magnetism in the Zintl compound Ba14MnBi11 is rather poorly understood. Experimental claims are largely inconsistent with ab initio calculations, much beyond typical errors of the latter. We revisit this old problem, assuming that the root of the problem may be in nonstoichiometry of existing samples. Our key finding is that the magnetic ground state is indeed very susceptible to charge doping (band filling). Calculations for stoichiometric Ba14MnBi11 give a rather stable ferromagnetic metallic state, in agreement with previous publications. However, by adding exactly one electron per Mn, the system becomes semiconducting as expected, and becomes weakly antiferromagnetic (AF). On the other hand, upon small amount of hole doping, the system transitions to a special type of AF state known as altermagnetism. Furthermore, hole and electron doping-induced phase transitions result from different underlying mechanisms, influencing different exchange pathways. We propose that the inconsistency between experiment and theory is not a failure of the latter, but results from a nontrivial ramification of nonstoichiometry. The possibility of doping-stabilized altermagnetism is exciting.","PeriodicalId":501713,"journal":{"name":"npj Spintronics","volume":" ","pages":"1-7"},"PeriodicalIF":0.0,"publicationDate":"2024-10-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.nature.com/articles/s44306-024-00056-x.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142519198","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-10-14DOI: 10.1038/s44306-024-00060-1
Qiming Shao
Increasing the bandwidth of existing optical fiber networks is vital as society’s appetite for information grows. This Editorial presents a spintronics-based solution in the context of recent research findings.
{"title":"Communicating with magnons","authors":"Qiming Shao","doi":"10.1038/s44306-024-00060-1","DOIUrl":"10.1038/s44306-024-00060-1","url":null,"abstract":"Increasing the bandwidth of existing optical fiber networks is vital as society’s appetite for information grows. This Editorial presents a spintronics-based solution in the context of recent research findings.","PeriodicalId":501713,"journal":{"name":"npj Spintronics","volume":" ","pages":"1-1"},"PeriodicalIF":0.0,"publicationDate":"2024-10-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.nature.com/articles/s44306-024-00060-1.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142431069","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-10-05DOI: 10.1038/s44306-024-00055-y
Philipp Keßler, Laura Garcia-Gassull, Andreas Suter, Thomas Prokscha, Zaher Salman, Dmitry Khalyavin, Pascal Manuel, Fabio Orlandi, Igor I. Mazin, Roser Valentí, Simon Moser
Altermagnets are a novel class of magnetic materials, where magnetic order is staggered both in coordinate and momentum space. The metallic rutile oxide RuO2, long believed to be a textbook Pauli paramagnet, recently emerged as a putative workhorse altermagnet when resonant X-ray and neutron scattering studies reported nonzero magnetic moments and long-range collinear order. While some experiments seem consistent with altermagnetism, magnetic order in RuO2 remains controversial. We show that RuO2 is nonmagnetic, both in bulk and thin film. Muon spectroscopy complemented by density-functional theory finds at most 1.14 × 10−4 μB/Ru in bulk and at most 7.5 × 10−4 μB/Ru in 11 nm epitaxial films, at our spectrometers’ detection limit, and dramatically smaller than previously reported neutron results that were used to rationalize altermagnetic behavior. Our own neutron diffraction measurements on RuO2 single crystals identify multiple scattering as the source for the false signal in earlier studies.
{"title":"Absence of magnetic order in RuO2: insights from μSR spectroscopy and neutron diffraction","authors":"Philipp Keßler, Laura Garcia-Gassull, Andreas Suter, Thomas Prokscha, Zaher Salman, Dmitry Khalyavin, Pascal Manuel, Fabio Orlandi, Igor I. Mazin, Roser Valentí, Simon Moser","doi":"10.1038/s44306-024-00055-y","DOIUrl":"10.1038/s44306-024-00055-y","url":null,"abstract":"Altermagnets are a novel class of magnetic materials, where magnetic order is staggered both in coordinate and momentum space. The metallic rutile oxide RuO2, long believed to be a textbook Pauli paramagnet, recently emerged as a putative workhorse altermagnet when resonant X-ray and neutron scattering studies reported nonzero magnetic moments and long-range collinear order. While some experiments seem consistent with altermagnetism, magnetic order in RuO2 remains controversial. We show that RuO2 is nonmagnetic, both in bulk and thin film. Muon spectroscopy complemented by density-functional theory finds at most 1.14 × 10−4 μB/Ru in bulk and at most 7.5 × 10−4 μB/Ru in 11 nm epitaxial films, at our spectrometers’ detection limit, and dramatically smaller than previously reported neutron results that were used to rationalize altermagnetic behavior. Our own neutron diffraction measurements on RuO2 single crystals identify multiple scattering as the source for the false signal in earlier studies.","PeriodicalId":501713,"journal":{"name":"npj Spintronics","volume":" ","pages":"1-8"},"PeriodicalIF":0.0,"publicationDate":"2024-10-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.nature.com/articles/s44306-024-00055-y.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142383564","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-10-01DOI: 10.1038/s44306-024-00044-1
V. D. Nguyen, S. Rao, K. Wostyn, S. Couet
Spin-orbit torque magnetic random-access memory (SOT-MRAM) offers promise for fast operation and high endurance but faces challenges such as low switching current, reliable field free switching, and back-end of line manufacturing processes. We review recent advancements in perpendicular SOT-MRAM devices, emphasizing on material developments to enhance charge-spin conversion efficiency and large-scale device integration strategies. We also discuss the remaining challenges in achieving a single device with low switching current, reliable field free switching to unlock the full potential of SOT-MRAM technology.
{"title":"Recent progress in spin-orbit torque magnetic random-access memory","authors":"V. D. Nguyen, S. Rao, K. Wostyn, S. Couet","doi":"10.1038/s44306-024-00044-1","DOIUrl":"10.1038/s44306-024-00044-1","url":null,"abstract":"Spin-orbit torque magnetic random-access memory (SOT-MRAM) offers promise for fast operation and high endurance but faces challenges such as low switching current, reliable field free switching, and back-end of line manufacturing processes. We review recent advancements in perpendicular SOT-MRAM devices, emphasizing on material developments to enhance charge-spin conversion efficiency and large-scale device integration strategies. We also discuss the remaining challenges in achieving a single device with low switching current, reliable field free switching to unlock the full potential of SOT-MRAM technology.","PeriodicalId":501713,"journal":{"name":"npj Spintronics","volume":" ","pages":"1-15"},"PeriodicalIF":0.0,"publicationDate":"2024-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.nature.com/articles/s44306-024-00044-1.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142360067","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Achieving the full understanding and control of the insulator-to-metal transition in Mott materials is key for the next generation of electronics devices, with applications ranging from ultrafast transistors, volatile and non-volatile memories and artificial neurons for neuromorphic computing. In this work, we will review the state-of-the-art knowledge of the Mott transition, with specific focus on materials of relevance for actual devices, such as vanadium and other transition metal oxides and chalcogenides. We will emphasize the current attempts in controlling the Mott switching dynamics via the application of external voltage and electromagnetic pulses and we will discuss how the recent advances in time- and space-resolved techniques are boosting the comprehension of the firing process. The nature of the voltage/light-induced Mott switching is inherently different from what is attainable by the slower variation of thermodynamic parameters, thus offering promising routes to achieving the reversible and ultrafast control of conductivity and magnetism in Mott nanodevices.
{"title":"Mott materials: unsuccessful metals with a bright future","authors":"Alessandra Milloch, Michele Fabrizio, Claudio Giannetti","doi":"10.1038/s44306-024-00047-y","DOIUrl":"10.1038/s44306-024-00047-y","url":null,"abstract":"Achieving the full understanding and control of the insulator-to-metal transition in Mott materials is key for the next generation of electronics devices, with applications ranging from ultrafast transistors, volatile and non-volatile memories and artificial neurons for neuromorphic computing. In this work, we will review the state-of-the-art knowledge of the Mott transition, with specific focus on materials of relevance for actual devices, such as vanadium and other transition metal oxides and chalcogenides. We will emphasize the current attempts in controlling the Mott switching dynamics via the application of external voltage and electromagnetic pulses and we will discuss how the recent advances in time- and space-resolved techniques are boosting the comprehension of the firing process. The nature of the voltage/light-induced Mott switching is inherently different from what is attainable by the slower variation of thermodynamic parameters, thus offering promising routes to achieving the reversible and ultrafast control of conductivity and magnetism in Mott nanodevices.","PeriodicalId":501713,"journal":{"name":"npj Spintronics","volume":" ","pages":"1-10"},"PeriodicalIF":0.0,"publicationDate":"2024-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.nature.com/articles/s44306-024-00047-y.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142360068","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Magnons and phonons are engineered in artificial lattices with tunable modes and band dispersions. Recent advance in magnon-phonon coupling shined a light on combining magnonic and phononic crystals as hybrid magnon-phonon crystals, benefit from the tunable magnon-phonon coupling, the time-reversal symmetry breaking of magnons, and the long lifetime of phonons. This perspective summarizes lattice-based mutual control of magnons and phonons, and proposes the opportunities provided by the hybrid magnon-phonon crystals.
{"title":"Hybrid magnon-phonon crystals","authors":"Liyang Liao, Jiacheng Liu, Jorge Puebla, Qiming Shao, Yoshichika Otani","doi":"10.1038/s44306-024-00052-1","DOIUrl":"10.1038/s44306-024-00052-1","url":null,"abstract":"Magnons and phonons are engineered in artificial lattices with tunable modes and band dispersions. Recent advance in magnon-phonon coupling shined a light on combining magnonic and phononic crystals as hybrid magnon-phonon crystals, benefit from the tunable magnon-phonon coupling, the time-reversal symmetry breaking of magnons, and the long lifetime of phonons. This perspective summarizes lattice-based mutual control of magnons and phonons, and proposes the opportunities provided by the hybrid magnon-phonon crystals.","PeriodicalId":501713,"journal":{"name":"npj Spintronics","volume":" ","pages":"1-6"},"PeriodicalIF":0.0,"publicationDate":"2024-09-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.nature.com/articles/s44306-024-00052-1.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142137874","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-09-02DOI: 10.1038/s44306-024-00053-0
Theodoros Adamantopoulos, Maximilian Merte, Frank Freimuth, Dongwook Go, Lishu Zhang, Marjana Ležaić, Wanxiang Feng, Yugui Yao, Jairo Sinova, Libor Šmejkal, Stefan Blügel, Yuriy Mokrousov
While the understanding of altermagnetism is still at a very early stage, it is expected to play a role in various fields of condensed matter research, for example spintronics, caloritronics and superconductivity. In the field of optical magnetism, it is still unclear to which extent altermagnets as a class can exhibit a distinct behavior. Here we choose RuO2, a prototype metallic altermagnet with a giant spin splitting, and CoF2, an experimentally known insulating altermagnet, to study the light-induced magnetism in rutile altermagnets from first-principles. We demonstrate that in the non-relativisic limit the allowed sublattice-resolved orbital response exhibits symmetries, imposed by altermagnetism, which lead to a drastic canting of light-induced moments. On the other hand, we find that inclusion of spin-orbit interaction enhances the overall effect drastically, introduces a significant anisotropy with respect to the light polarization and strongly suppresses the canting of induced moments. Remarkably, we observe that the moments induced by linearly-polarized laser pulses in light altermagnets can even exceed in magnitude those predicted for heavy ferromagnets exposed to circularly polarized light. By resorting to microscopic tools we interpret our results in terms of the altermagnetic spin splittings and of their reciprocal space distribution. Based on our findings, we speculate that optical excitations may provide a unique tool to switch and probe the magnetic state of rutile altermagnets.
{"title":"Spin and orbital magnetism by light in rutile altermagnets","authors":"Theodoros Adamantopoulos, Maximilian Merte, Frank Freimuth, Dongwook Go, Lishu Zhang, Marjana Ležaić, Wanxiang Feng, Yugui Yao, Jairo Sinova, Libor Šmejkal, Stefan Blügel, Yuriy Mokrousov","doi":"10.1038/s44306-024-00053-0","DOIUrl":"10.1038/s44306-024-00053-0","url":null,"abstract":"While the understanding of altermagnetism is still at a very early stage, it is expected to play a role in various fields of condensed matter research, for example spintronics, caloritronics and superconductivity. In the field of optical magnetism, it is still unclear to which extent altermagnets as a class can exhibit a distinct behavior. Here we choose RuO2, a prototype metallic altermagnet with a giant spin splitting, and CoF2, an experimentally known insulating altermagnet, to study the light-induced magnetism in rutile altermagnets from first-principles. We demonstrate that in the non-relativisic limit the allowed sublattice-resolved orbital response exhibits symmetries, imposed by altermagnetism, which lead to a drastic canting of light-induced moments. On the other hand, we find that inclusion of spin-orbit interaction enhances the overall effect drastically, introduces a significant anisotropy with respect to the light polarization and strongly suppresses the canting of induced moments. Remarkably, we observe that the moments induced by linearly-polarized laser pulses in light altermagnets can even exceed in magnitude those predicted for heavy ferromagnets exposed to circularly polarized light. By resorting to microscopic tools we interpret our results in terms of the altermagnetic spin splittings and of their reciprocal space distribution. Based on our findings, we speculate that optical excitations may provide a unique tool to switch and probe the magnetic state of rutile altermagnets.","PeriodicalId":501713,"journal":{"name":"npj Spintronics","volume":" ","pages":"1-10"},"PeriodicalIF":0.0,"publicationDate":"2024-09-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.nature.com/articles/s44306-024-00053-0.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142117952","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The realization and control of exchange bias (EB) are highly desirable for spintronic applications. All-oxide heterostructures comprised of ferromagnetic and antiferromagnetic/multiferroic oxides provide an ideal platform to enable the electric-field control of EB, promising for energy-efficient memory and logic devices. However, the low block temperature (TB) and small bias field (HEB) hinder further advances towards room-temperature applications. Here, we report an alternative approach to enhance the interface-induced EB by using ferrimagnetic double-perovskite with B-site cation ordering. In heterostructures comprised of double-perovskite Sr2FeReO6 (SFRO) and LaFeO3 (LFO), a high TB (about 250 K) and large HEB are observed, which is significantly larger than the counterparts with LFO and ferromagnetic oxides. Further analysis suggests that the cation-ordering and ferrimagnetic spin structure of the double-perovskite could contribute significantly to the enhanced exchanged bias when interfacing with G-type antiferromagnets. Our results open a new avenue for developing all-oxides heterostructures for future magnetic technologies.
在自旋电子应用中，实现和控制交换偏压（EB）是非常理想的。由铁磁性和反铁磁性/多铁氧体组成的全氧化物异质结构为实现 EB 的电场控制提供了一个理想平台，有望用于高能效存储器和逻辑器件。然而，低阻滞温度（TB）和小偏置场（HEB）阻碍了室温应用的进一步发展。在此，我们报告了一种通过使用具有 B 位阳离子有序化的铁磁性双超晶石来增强界面诱导 EB 的替代方法。在由双过氧化物 Sr2FeReO6（SFRO）和 LaFeO3（LFO）组成的异质结构中，我们观察到了高 TB（约 250 K）和大 HEB，这明显大于 LFO 和铁磁氧化物的对应物。进一步的分析表明，当与 G 型反铁磁体相互作用时，双超沸石的阳离子排序和铁磁性自旋结构可能会对增强交换偏压做出重要贡献。我们的研究结果为开发未来磁性技术的全氧化物异质结构开辟了一条新途径。
{"title":"Enhanced exchange bias in all-oxide heterostructures with cation-ordered ferrimagnetic double-perovskite","authors":"Xiaofu Qiu, Zelin Wang, Hetian Chen, Yuhan Liang, Xiaoyu Jiang, Yujun Zhang, Jing Ma, Fangyuan Zhu, Tianxiang Nan, Zhen Chen, Di Yi","doi":"10.1038/s44306-024-00051-2","DOIUrl":"10.1038/s44306-024-00051-2","url":null,"abstract":"The realization and control of exchange bias (EB) are highly desirable for spintronic applications. All-oxide heterostructures comprised of ferromagnetic and antiferromagnetic/multiferroic oxides provide an ideal platform to enable the electric-field control of EB, promising for energy-efficient memory and logic devices. However, the low block temperature (TB) and small bias field (HEB) hinder further advances towards room-temperature applications. Here, we report an alternative approach to enhance the interface-induced EB by using ferrimagnetic double-perovskite with B-site cation ordering. In heterostructures comprised of double-perovskite Sr2FeReO6 (SFRO) and LaFeO3 (LFO), a high TB (about 250 K) and large HEB are observed, which is significantly larger than the counterparts with LFO and ferromagnetic oxides. Further analysis suggests that the cation-ordering and ferrimagnetic spin structure of the double-perovskite could contribute significantly to the enhanced exchanged bias when interfacing with G-type antiferromagnets. Our results open a new avenue for developing all-oxides heterostructures for future magnetic technologies.","PeriodicalId":501713,"journal":{"name":"npj Spintronics","volume":" ","pages":"1-6"},"PeriodicalIF":0.0,"publicationDate":"2024-08-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.nature.com/articles/s44306-024-00051-2.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141973730","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-08-13DOI: 10.1038/s44306-024-00046-z
Ruben Dario Gonzalez Betancourt, Jan Zubáč, Kevin Geishendorf, Philipp Ritzinger, Barbora Růžičková, Tommy Kotte, Jakub Železný, Kamil Olejník, Gunther Springholz, Bernd Büchner, Andy Thomas, Karel Výborný, Tomas Jungwirth, Helena Reichlová, Dominik Kriegner
Recently, MnTe was established as an altermagnetic material that hosts spin-polarized electronic bands as well as anomalous transport effects like the anomalous Hall effect. In addition to these effects arising from altermagnetism, MnTe also hosts other magnetoresistance effects. Here, we study the manipulation of the magnetic order by an applied magnetic field and its impact on the electrical resistivity. In particular, we establish which components of anisotropic magnetoresistance are present when the magnetic order is rotated within the hexagonal basal plane. Our experimental results, which are in agreement with our symmetry analysis of the magnetotransport components, showcase the existence of an anisotropic magnetoresistance linked to both the relative orientation of current and magnetic order, as well as crystal and magnetic order. Altermagnetism is manifested as a three-fold component in the transverse magnetoresistance which arises due to the anomalous Hall effect.
{"title":"Anisotropic magnetoresistance in altermagnetic MnTe","authors":"Ruben Dario Gonzalez Betancourt, Jan Zubáč, Kevin Geishendorf, Philipp Ritzinger, Barbora Růžičková, Tommy Kotte, Jakub Železný, Kamil Olejník, Gunther Springholz, Bernd Büchner, Andy Thomas, Karel Výborný, Tomas Jungwirth, Helena Reichlová, Dominik Kriegner","doi":"10.1038/s44306-024-00046-z","DOIUrl":"10.1038/s44306-024-00046-z","url":null,"abstract":"Recently, MnTe was established as an altermagnetic material that hosts spin-polarized electronic bands as well as anomalous transport effects like the anomalous Hall effect. In addition to these effects arising from altermagnetism, MnTe also hosts other magnetoresistance effects. Here, we study the manipulation of the magnetic order by an applied magnetic field and its impact on the electrical resistivity. In particular, we establish which components of anisotropic magnetoresistance are present when the magnetic order is rotated within the hexagonal basal plane. Our experimental results, which are in agreement with our symmetry analysis of the magnetotransport components, showcase the existence of an anisotropic magnetoresistance linked to both the relative orientation of current and magnetic order, as well as crystal and magnetic order. Altermagnetism is manifested as a three-fold component in the transverse magnetoresistance which arises due to the anomalous Hall effect.","PeriodicalId":501713,"journal":{"name":"npj Spintronics","volume":" ","pages":"1-9"},"PeriodicalIF":0.0,"publicationDate":"2024-08-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.nature.com/articles/s44306-024-00046-z.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141973748","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-08-12DOI: 10.1038/s44306-024-00050-3
Takayuki Shiino, Phuoc Cao Van, Jong-Guk Choi, Geunwoo Kim, Jong-Ryul Jeong, Byong-Guk Park
Spin-orbit torque (SOT), arising from spin-orbit coupling-induced spin currents, provides efficient control of magnetization. SOT characterization involving harmonic Hall resistances is typically done in low-current regimes, distinct from high-current regimes, where SOT-induced magnetization switching occurs. In this study, we investigate azimuthal angle (ϕ)-dependent harmonic Hall resistances of a Pt/yttrium iron garnet (YIG) layer across a wide range of measurement currents. Under low-current conditions, conventional ϕ-dependent Hall resistances are observed; the first harmonic Hall resistance exhibits sin 2ϕ behavior and the second harmonic Hall resistance comprises cos ϕ and cos 3ϕ terms. Interestingly, with increasing current, higher-order angular-dependent terms become non-negligible, referring to the sin 4ϕ and sin 6ϕ terms for the first harmonic and the cos 5ϕ and cos 7ϕ terms for the second harmonic Hall resistances. We attribute this unconventional angular dependence to the nonlinear response of magnetization direction to SOT, emphasizing its relevance to understanding the magnetization dynamics during SOT-induced switching under large currents.
自旋轨道转矩（SOT）由自旋轨道耦合引起的自旋电流产生，可有效控制磁化。涉及谐波霍尔电阻的 SOT 特性分析通常是在低电流状态下进行的，有别于 SOT 引发磁化切换的高电流状态。在本研究中，我们研究了铂/钇铁石榴石（YIG）层在宽测量电流范围内与方位角（j）有关的谐波霍尔电阻。在低电流条件下，可以观察到传统的ϕ相关霍尔电阻；第一次谐波霍尔电阻表现为 sin 2ϕ，第二次谐波霍尔电阻包括 cos ϕ 和 cos 3ϕ。有趣的是，随着电流的增大，与角度相关的高阶项变得不可忽略，这指的是第一次谐波霍尔电阻的 sin 4j 和 sin 6j 项，以及第二次谐波霍尔电阻的 cos 5j 和 cos 7j 项。我们将这种非常规的角度依赖性归因于磁化方向对 SOT 的非线性响应，并强调其与理解大电流下 SOT 诱导开关期间的磁化动态相关。
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