We explore the pairing state and gap structure of UTe2 using a six-orbital model which we call the f–d–p model. Our model accurately reproduces the quasi-two-dimensional Fermi surfaces, agreeing with recent de Haas–van Alphen oscillation measurements and ((0, pm pi ,0)) antiferromagnetic spin fluctuations observed through neutron scattering. We incorporate on-site Coulomb repulsion for f electrons and solve the linearized Eliashberg equation within the third-order perturbation theory to investigate the superconducting symmetry in UTe2. An s-wave state featuring a highly anisotropic superconducting gap structure and a point-node–like behavior of the specific heat at low temperatures is identified as the most probable state.
我们使用一个六轨道模型来探索UTe2的配对态和间隙结构，我们称之为f-d-p模型。我们的模型精确地再现了准二维费米面，与最近的德哈斯-范阿尔芬振荡测量和通过中子散射观测到的（(0, pm pi ,0)）反铁磁自旋波动相吻合。我们将现场库仑斥力纳入 f 电子，并在三阶扰动理论中求解线性化的埃利亚斯伯格方程，以研究UTe2 的超导对称性。我们发现最有可能的状态是具有高度各向异性超导间隙结构和低温比热的点结状行为的 s 波态。
{"title":"Possible Unconventional s-Wave Pairing with Point-Node–Like Gap Structure in UTe2","authors":"Shingo Haruna, Takuji Nomura, Hirono Kaneyasu","doi":"10.7566/jpsj.93.063701","DOIUrl":"https://doi.org/10.7566/jpsj.93.063701","url":null,"abstract":"We explore the pairing state and gap structure of UTe<sub>2</sub> using a six-orbital model which we call the <i>f</i>–<i>d</i>–<i>p</i> model. Our model accurately reproduces the quasi-two-dimensional Fermi surfaces, agreeing with recent de Haas–van Alphen oscillation measurements and <tex-math space=\"preserve\" version=\"MathJax\">((0, pm pi ,0))</tex-math> antiferromagnetic spin fluctuations observed through neutron scattering. We incorporate on-site Coulomb repulsion for <i>f</i> electrons and solve the linearized Eliashberg equation within the third-order perturbation theory to investigate the superconducting symmetry in UTe<sub>2</sub>. An <i>s</i>-wave state featuring a highly anisotropic superconducting gap structure and a point-node–like behavior of the specific heat at low temperatures is identified as the most probable state.","PeriodicalId":17304,"journal":{"name":"Journal of the Physical Society of Japan","volume":"106 1","pages":""},"PeriodicalIF":1.7,"publicationDate":"2024-04-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140841568","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"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}
Md Asif Afzal, Yoshichika Ōnuki, Dai Aoki, Hisatomo Harima, Ryuji Higashinaka, Yuji Aoki, Tatsuma D. Matsuda
We grew high-quality single crystals of a ferromagnet SmNi2Cd20, an antiferromagnet SmPd2Cd20, and an antiferromagnet SmTi2Al20 with the cubic cage structure by the self-flux method and carried out the de Haas–van Alphen experiment to detect the large cyclotron effective masses of the main Fermi surfaces. This is because these compounds are reported to possess large electronic specific heat coefficients of 100–200 mJ/(K2·mol). We have succeeded in detecting the main Fermi surfaces. The corresponding cyclotron mass of a so-called valence-fluctuating compound SmTi2Al20 is surprisingly large, revealing 26 m0 (m0: rest mass of an electron). In SmTi2Al20, no Curie–Weiss term is found in the magnetic susceptibility, and the −log T dependence of the electrical resistivity is observed at low temperatures. On the other hand, the conventional masses of 2.1 m0 are obtained in SmNi2Cd20 and SmPd2Cd20, following the Curie–Weiss law in the magnetic susceptibility.
{"title":"Large Cyclotron Effective Masses in Antiferromagnet SmTi2Al20 Compared with Conventional Masses in Ferromagnet SmNi2Cd20 and Antiferromagnet SmPd2Cd20","authors":"Md Asif Afzal, Yoshichika Ōnuki, Dai Aoki, Hisatomo Harima, Ryuji Higashinaka, Yuji Aoki, Tatsuma D. Matsuda","doi":"10.7566/jpsj.93.054710","DOIUrl":"https://doi.org/10.7566/jpsj.93.054710","url":null,"abstract":"We grew high-quality single crystals of a ferromagnet SmNi<sub>2</sub>Cd<sub>20</sub>, an antiferromagnet SmPd<sub>2</sub>Cd<sub>20</sub>, and an antiferromagnet SmTi<sub>2</sub>Al<sub>20</sub> with the cubic cage structure by the self-flux method and carried out the de Haas–van Alphen experiment to detect the large cyclotron effective masses of the main Fermi surfaces. This is because these compounds are reported to possess large electronic specific heat coefficients of 100–200 mJ/(K<sup>2</sup>·mol). We have succeeded in detecting the main Fermi surfaces. The corresponding cyclotron mass of a so-called valence-fluctuating compound SmTi<sub>2</sub>Al<sub>20</sub> is surprisingly large, revealing 26 <i>m</i><sub>0</sub> (<i>m</i><sub>0</sub>: rest mass of an electron). In SmTi<sub>2</sub>Al<sub>20</sub>, no Curie–Weiss term is found in the magnetic susceptibility, and the −log <i>T</i> dependence of the electrical resistivity is observed at low temperatures. On the other hand, the conventional masses of 2.1 <i>m</i><sub>0</sub> are obtained in SmNi<sub>2</sub>Cd<sub>20</sub> and SmPd<sub>2</sub>Cd<sub>20</sub>, following the Curie–Weiss law in the magnetic susceptibility.","PeriodicalId":17304,"journal":{"name":"Journal of the Physical Society of Japan","volume":"34 1","pages":""},"PeriodicalIF":1.7,"publicationDate":"2024-04-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140799037","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"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}
Superconducting transition, defined as vanishing of the resistivity, under a magnetic field in a clean bulk type II superconductor with weak sample disorder is believed to be a reflection of freezing of the vortex liquid to a kind of vortex solids. This fundamental issue on superconductivity is examined in detail. Based on the Ginzburg–Landau fluctuation theory for a three-dimensional (3D) system and through a supplementary study in 2D case, we find that the resistivity in the weakly disordered 3D case vanishes in a nearly discontinuous way, reflecting growth of the Bragg peaks on approaching the vortex lattice melting transition. In contrast, such a sharp decrease of the resistivity does not clearly appear in the corresponding 2D case. The consequences of this difference in the vanishing behavior of the resistivity between the 2D and 3D systems are discussed in relation to available experimental facts.
在磁场作用下，具有弱样品无序性的纯净块状 II 型超导体中的超导转变（定义为电阻率消失）被认为是涡流液体冻结为一种涡流固体的反映。本文详细研究了超导这一基本问题。基于三维（3D）系统的金兹堡-朗道波动理论，并通过对二维情况的补充研究，我们发现在弱无序的三维情况下，电阻率以近乎不连续的方式消失，这反映了在接近涡旋晶格熔化转变时布拉格峰的增长。相比之下，电阻率的这种急剧下降在相应的二维情况下并不明显。本文结合现有的实验事实，讨论了二维和三维系统之间电阻率消失行为的这种差异所产生的后果。
{"title":"Vanishing of Resistivity upon Freezing of Vortex Liquid in Clean Superconductors","authors":"Naratip Nunchot, Ryusuke Ikeda","doi":"10.7566/jpsj.93.054712","DOIUrl":"https://doi.org/10.7566/jpsj.93.054712","url":null,"abstract":"Superconducting transition, defined as vanishing of the resistivity, under a magnetic field in a clean bulk type II superconductor with weak sample disorder is believed to be a reflection of freezing of the vortex liquid to a kind of vortex solids. This fundamental issue on superconductivity is examined in detail. Based on the Ginzburg–Landau fluctuation theory for a three-dimensional (3D) system and through a supplementary study in 2D case, we find that the resistivity in the weakly disordered 3D case vanishes in a nearly discontinuous way, reflecting growth of the Bragg peaks on approaching the vortex lattice melting transition. In contrast, such a sharp decrease of the resistivity does not clearly appear in the corresponding 2D case. The consequences of this difference in the vanishing behavior of the resistivity between the 2D and 3D systems are discussed in relation to available experimental facts.","PeriodicalId":17304,"journal":{"name":"Journal of the Physical Society of Japan","volume":"229 1","pages":""},"PeriodicalIF":1.7,"publicationDate":"2024-04-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140798846","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"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}
Noriaki Hamada, Satoshi Nakamura, Kenta Takahashi, Mario Okawa, Tomohiko Saitoh
In order to reproduce experimental photoemission spectroscopy (PES) data by using band structure calculations with linearized augmented-plane-wave method, we developed a new method to calculate the atomic-subshell photoelectron differential cross section (PE-DCS) of the valence band. PE-DCS was calculated to be the sum of the products of the partial density of states (PDOS) and the photoionization differential cross section (PI-DCS) of each atomic subshell. To construct an appropriate PDOS beyond the conventional muffin-tin sphere (MTS) PDOS, we proposed a “nearly-neutral atomic sphere”, which can be defined as a natural extension of MTS. Although the calculational method for atomic-subshell PI-DCS was the standard Hartree–Fock–Slater method, we developed a new computer code in order to deal with the unoccupied electron shells in the ground state of isolated atoms up to ∼10 keV. Details of the PE-DCS calculations were examined by using two simple examples of Na metal and NaCl, and then, the method was applied to hard x-ray PES (HX-PES) data of CuAlO2. The experimental spectra were satisfactorily reproduced, demonstrating the potential applications of our method to HX-PES spectra of many compounds.
为了通过线性化增强平面波方法的能带结构计算来重现实验光发射光谱（PES）数据，我们开发了一种新方法来计算价带的原子子壳光电子微分截面（PE-DCS）。计算得出的 PE-DCS 是每个原子子壳的部分态密度（PDOS）和光离子化微分截面（PI-DCS）的乘积之和。为了在传统的松饼锡球（MTS）部分态密度之外构建合适的部分态密度，我们提出了 "近中性原子球"，它可以被定义为 MTS 的自然扩展。虽然原子子壳 PI-DCS 的计算方法是标准的哈特里-福克-斯莱特方法，但我们开发了一种新的计算机代码，以处理孤立原子基态中高达 ∼10 keV 的未占电子壳。我们以 Na metal 和 NaCl 两个简单的例子考察了 PE-DCS 计算的细节，然后将该方法应用于 CuAlO2 的硬 X 射线 PES（HX-PES）数据。实验光谱得到了令人满意的再现，这表明我们的方法有可能应用于许多化合物的 HX-PES 光谱。
{"title":"Realistic Simulation of Valence-Band Photoemission Spectra by Using First-Principles Calculations on the Basis of FLAPW Method","authors":"Noriaki Hamada, Satoshi Nakamura, Kenta Takahashi, Mario Okawa, Tomohiko Saitoh","doi":"10.7566/jpsj.93.054709","DOIUrl":"https://doi.org/10.7566/jpsj.93.054709","url":null,"abstract":"In order to reproduce experimental photoemission spectroscopy (PES) data by using band structure calculations with linearized augmented-plane-wave method, we developed a new method to calculate the atomic-subshell photoelectron differential cross section (PE-DCS) of the valence band. PE-DCS was calculated to be the sum of the products of the partial density of states (PDOS) and the photoionization differential cross section (PI-DCS) of each atomic subshell. To construct an appropriate PDOS beyond the conventional muffin-tin sphere (MTS) PDOS, we proposed a “nearly-neutral atomic sphere”, which can be defined as a natural extension of MTS. Although the calculational method for atomic-subshell PI-DCS was the standard Hartree–Fock–Slater method, we developed a new computer code in order to deal with the unoccupied electron shells in the ground state of isolated atoms up to ∼10 keV. Details of the PE-DCS calculations were examined by using two simple examples of Na metal and NaCl, and then, the method was applied to hard x-ray PES (HX-PES) data of CuAlO<sub>2</sub>. The experimental spectra were satisfactorily reproduced, demonstrating the potential applications of our method to HX-PES spectra of many compounds.","PeriodicalId":17304,"journal":{"name":"Journal of the Physical Society of Japan","volume":"83 1","pages":""},"PeriodicalIF":1.7,"publicationDate":"2024-04-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140798913","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"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}
We calculate the RKKY interactions derived from ab initio calculations for the intermetallic compound CeCoSi exhibiting the hidden nonmagnetic order at T0 and examine the instability towards possible multipole orders within the random phase approximation. All 36 multipole interactions up to rank 5 are investigated, and the maximum susceptibility exhibits an antiferro order with q = 0 for nonmagnetic multipoles of monopole I and hexadecapole H0, yielding a charge imbalance of f electrons at two Ce atoms in the unit cell. The obtained order can explain some experiments.
我们计算了金属间化合物 CeCoSi 在 T0 时表现出隐藏非磁性阶的 RKKY 相互作用，并考察了随机相近似中可能存在的多极阶的不稳定性。研究了秩 5 以下的所有 36 种多极相互作用，对于单极 I 和十六极 H0 的非磁性多极，最大电感表现出 q = 0 的反铁磁阶，在单位晶胞中的两个 Ce 原子上产生 f 电子的电荷不平衡。所得到的阶可以解释一些实验。
{"title":"RKKY Interactions and Multipole Order in Ab initio Wannier Model of CeCoSi","authors":"Takemi Yamada, Yuki Yanagi, Keisuke Mitsumoto","doi":"10.7566/jpsj.93.053703","DOIUrl":"https://doi.org/10.7566/jpsj.93.053703","url":null,"abstract":"We calculate the RKKY interactions derived from ab initio calculations for the intermetallic compound CeCoSi exhibiting the hidden nonmagnetic order at <i>T</i><sub>0</sub> and examine the instability towards possible multipole orders within the random phase approximation. All 36 multipole interactions up to rank 5 are investigated, and the maximum susceptibility exhibits an antiferro order with <b><i>q</i></b> = <b>0</b> for nonmagnetic multipoles of monopole <i>I</i> and hexadecapole <i>H</i><sub>0</sub>, yielding a charge imbalance of <i>f</i> electrons at two Ce atoms in the unit cell. The obtained order can explain some experiments.","PeriodicalId":17304,"journal":{"name":"Journal of the Physical Society of Japan","volume":"25 1","pages":""},"PeriodicalIF":1.7,"publicationDate":"2024-04-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140636523","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"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}
Kai Ito, Hironori Shimakura, Shuta Tahara, Koji Ohara, Akihide Koura, Kohei Shimamura, Fuyuki Shimojo
The structural and bonding properties of liquid L-lactic acid were investigated through ab initio molecular dynamics simulations, leveraging on the agreement between the static structure factors obtained from high-energy X-ray diffraction (HEXRD) measurements. It has been demonstrated that predominant intermolecular interactions arise from hydrogen bonding. Hydrogen atoms in two hydroxy groups tend to form hydrogen bonds with two of the three oxygen atoms in neighboring molecules. This results in the presence of an oxygen atom in the hydroxy group of the carboxy group that does not significantly contribute to hydrogen bond formation with neighboring hydrogen atoms. This is consistent with the behavior observed in the crystalline phase. However, in the liquid state, four types of intermolecular hydrogen bonds are primarily formed, whereas in the crystal, only two types are observed. We show that the directionality of hydrogen bonds determines the intermolecular orientation. We thoroughly studied the structural properties and covalent bonding between atoms and charged states of atoms.
利用高能 X 射线衍射（HEXRD）测量得到的静态结构因子之间的一致性，通过 ab initio 分子动力学模拟研究了液态 L-乳酸的结构和键合特性。结果表明，分子间的主要相互作用来自氢键。两个羟基中的氢原子倾向于与相邻分子中三个氧原子中的两个形成氢键。这导致羧基羟基中的一个氧原子对与邻近氢原子形成氢键的作用不大。这与在结晶相中观察到的行为一致。然而，在液态中，主要形成四种类型的分子间氢键，而在晶体中只观察到两种类型。我们发现氢键的方向性决定了分子间的取向。我们深入研究了原子和原子带电状态之间的结构特性和共价键。
{"title":"Intermolecular Correlations in Liquid Lactic Acid Based on ab initio Molecular Dynamics Simulations Combined with High-Energy X-ray Diffraction Measurements","authors":"Kai Ito, Hironori Shimakura, Shuta Tahara, Koji Ohara, Akihide Koura, Kohei Shimamura, Fuyuki Shimojo","doi":"10.7566/jpsj.93.054601","DOIUrl":"https://doi.org/10.7566/jpsj.93.054601","url":null,"abstract":"The structural and bonding properties of liquid L-lactic acid were investigated through ab initio molecular dynamics simulations, leveraging on the agreement between the static structure factors obtained from high-energy X-ray diffraction (HEXRD) measurements. It has been demonstrated that predominant intermolecular interactions arise from hydrogen bonding. Hydrogen atoms in two hydroxy groups tend to form hydrogen bonds with two of the three oxygen atoms in neighboring molecules. This results in the presence of an oxygen atom in the hydroxy group of the carboxy group that does not significantly contribute to hydrogen bond formation with neighboring hydrogen atoms. This is consistent with the behavior observed in the crystalline phase. However, in the liquid state, four types of intermolecular hydrogen bonds are primarily formed, whereas in the crystal, only two types are observed. We show that the directionality of hydrogen bonds determines the intermolecular orientation. We thoroughly studied the structural properties and covalent bonding between atoms and charged states of atoms.","PeriodicalId":17304,"journal":{"name":"Journal of the Physical Society of Japan","volume":"40 1","pages":""},"PeriodicalIF":1.7,"publicationDate":"2024-04-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140636904","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"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}
We study low-lying spin-singlet excitations of two-leg Hubbard ladders with site-dependent potentials. Using general formulas of the charge disproportionation induced by the site-dependent potentials, we derive the contributions of spin degrees of freedom to the spectral functions such as the dynamical charge structure factor (N(boldsymbol{k},omega )) and the optical conductivity σγ(ω) along the γ (( = x,y))-direction of the two-leg ladders. Numerical results obtained by the Lanczos diagonalization method have clarified that the multi-triplon singlet states, including two- and three-triplon excitations, can be detected by observing these quantities. Furthermore, we have found that ladders with random potentials also have non-negligible contributions of these excitations to σx(ω).
{"title":"Multi-Triplon Excitations of Hubbard Ladders with Site-Dependent Potentials","authors":"Nobuya Maeshima, Ken-ichi Hino","doi":"10.7566/jpsj.93.054707","DOIUrl":"https://doi.org/10.7566/jpsj.93.054707","url":null,"abstract":"We study low-lying spin-singlet excitations of two-leg Hubbard ladders with site-dependent potentials. Using general formulas of the charge disproportionation induced by the site-dependent potentials, we derive the contributions of spin degrees of freedom to the spectral functions such as the dynamical charge structure factor <tex-math space=\"preserve\" version=\"MathJax\">(N(boldsymbol{k},omega ))</tex-math> and the optical conductivity <i>σ<sub>γ</sub></i>(<i>ω</i>) along the <i>γ</i> (<tex-math space=\"preserve\" version=\"MathJax\">( = x,y)</tex-math>)-direction of the two-leg ladders. Numerical results obtained by the Lanczos diagonalization method have clarified that the multi-triplon singlet states, including two- and three-triplon excitations, can be detected by observing these quantities. Furthermore, we have found that ladders with random potentials also have non-negligible contributions of these excitations to <i>σ<sub>x</sub></i>(<i>ω</i>).","PeriodicalId":17304,"journal":{"name":"Journal of the Physical Society of Japan","volume":"44 1","pages":""},"PeriodicalIF":1.7,"publicationDate":"2024-04-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140636537","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"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}
Hongkun Guo, Huili Fan, Hui He, Liwen Cheng, Huibo Fan
We propose and investigate a fiber-optic sensor of As2Se3 chalcogenide (ChG) microfiber laterally adhered on the hollow-core fiber (HCF) end face. HCF is fused with a single-mode fiber to form Fabry–Perot interferometer (FPI) between single-mode fiber (SMF) end face and ChG microfiber. ChG microfiber is ultra-sensitive to the small perturbations in the surroundings, because of its high refractive index and small Young’s modulus. Furthermore, relative to traditional fiber-optic FPI comprised by thin film, our proposed FPI with thin-diameter ChG microfiber could respond to mechanical vibrations over a broad range of frequencies. Based on finite-element simulation, ChG microfiber has ultra-broadband dynamic frequency response, up to several hundreds of megahertz accompanied by a very small response strength decay, in comparison to the frequency response of ChG film which is typically less than 30 MHz. ChG microfiber-based FPI is also used in the static refractometric sensing with sensitivity of 1563 nm/RIU. Such a novel fiber-optic sensor offers excellent potential for the nondestructive detection and advanced biomedical sensing.
{"title":"Investigation of Vibration and Sensing of Chalcogenide Microfiber Integrated with Hollow-core Fiber","authors":"Hongkun Guo, Huili Fan, Hui He, Liwen Cheng, Huibo Fan","doi":"10.7566/jpsj.93.054401","DOIUrl":"https://doi.org/10.7566/jpsj.93.054401","url":null,"abstract":"We propose and investigate a fiber-optic sensor of As<sub>2</sub>Se<sub>3</sub> chalcogenide (ChG) microfiber laterally adhered on the hollow-core fiber (HCF) end face. HCF is fused with a single-mode fiber to form Fabry–Perot interferometer (FPI) between single-mode fiber (SMF) end face and ChG microfiber. ChG microfiber is ultra-sensitive to the small perturbations in the surroundings, because of its high refractive index and small Young’s modulus. Furthermore, relative to traditional fiber-optic FPI comprised by thin film, our proposed FPI with thin-diameter ChG microfiber could respond to mechanical vibrations over a broad range of frequencies. Based on finite-element simulation, ChG microfiber has ultra-broadband dynamic frequency response, up to several hundreds of megahertz accompanied by a very small response strength decay, in comparison to the frequency response of ChG film which is typically less than 30 MHz. ChG microfiber-based FPI is also used in the static refractometric sensing with sensitivity of 1563 nm/RIU. Such a novel fiber-optic sensor offers excellent potential for the nondestructive detection and advanced biomedical sensing.","PeriodicalId":17304,"journal":{"name":"Journal of the Physical Society of Japan","volume":"67 1","pages":""},"PeriodicalIF":1.7,"publicationDate":"2024-04-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140615465","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"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}
M. O. Ajeesh, Joe D. Thompson, Eric D. Bauer, Filip Ronning, Sean M. Thomas, Priscila F. S. Rosa
We report the temperature–pressure phase diagram of a UTe2 single crystal that does not undergo a bulk superconducting transition but shows filamentary superconductivity with a critical transition temperature of 1 K at ambient pressure. Electrical-resistivity measurements reveal that the evolution of the filamentary superconducting state under pressure resembles the behavior observed in previous reports on bulk superconducting samples. AC calorimetry, however, does not show evidence for either bulk superconductivity or magnetism for pressures up to 1.6 GPa. Our results highlight the role of inhomogeneity in chemical-vapor-transport-grown UTe2 samples and serve as a cautionary tale when probing electrical resistivity alone.
{"title":"Hydrostatic Pressure Studies on Non-Superconducting UTe2","authors":"M. O. Ajeesh, Joe D. Thompson, Eric D. Bauer, Filip Ronning, Sean M. Thomas, Priscila F. S. Rosa","doi":"10.7566/jpsj.93.055001","DOIUrl":"https://doi.org/10.7566/jpsj.93.055001","url":null,"abstract":"We report the temperature–pressure phase diagram of a UTe<sub>2</sub> single crystal that does not undergo a bulk superconducting transition but shows filamentary superconductivity with a critical transition temperature of 1 K at ambient pressure. Electrical-resistivity measurements reveal that the evolution of the filamentary superconducting state under pressure resembles the behavior observed in previous reports on bulk superconducting samples. AC calorimetry, however, does not show evidence for either bulk superconductivity or magnetism for pressures up to 1.6 GPa. Our results highlight the role of inhomogeneity in chemical-vapor-transport-grown UTe<sub>2</sub> samples and serve as a cautionary tale when probing electrical resistivity alone.","PeriodicalId":17304,"journal":{"name":"Journal of the Physical Society of Japan","volume":"89 1","pages":""},"PeriodicalIF":1.7,"publicationDate":"2024-04-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140576339","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"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}
We attempted to evaluate the exchange stiffness constant, A(T) of fcc-Fe0.2Ni0.8 and L10-type FePt at finite temperatures employing the first-principles calculation. The spin fluctuation at a finite temperature was handled using the coherent potential approximation under the disordered-local-moment picture, and the A(T) was evaluated based on the free energy of spin spiral structure created in the effective medium representing the fluctuating spins. For fcc-Fe0.2Ni0.8, calculated A(0) was approximately 10 meV/Å. With increasing temperature, A(T) exhibits a linear-like decrease and becomes approximately 7 meV/Å at around room temperature which is in the range of experimentally expected value. This behavior somewhat deviates from the theoretical prediction considering a magnon–magnon scattering in the Heisenberg model. For FePt, we found a considerable anisotropy between A001(T) and A100(T) for spiral wave vectors along the directions of 〈001〉 and 〈100〉, respectively.
{"title":"Evaluation of the Exchange Stiffness Constants of Itinerant Magnets at Finite Temperatures from the First-Principles Calculations","authors":"Akimasa Sakuma","doi":"10.7566/jpsj.93.054705","DOIUrl":"https://doi.org/10.7566/jpsj.93.054705","url":null,"abstract":"We attempted to evaluate the exchange stiffness constant, <i>A</i>(<i>T</i>) of fcc-Fe<sub>0.2</sub>Ni<sub>0.8</sub> and <i>L</i>1<sub>0</sub>-type FePt at finite temperatures employing the first-principles calculation. The spin fluctuation at a finite temperature was handled using the coherent potential approximation under the disordered-local-moment picture, and the <i>A</i>(<i>T</i>) was evaluated based on the free energy of spin spiral structure created in the effective medium representing the fluctuating spins. For fcc-Fe<sub>0.2</sub>Ni<sub>0.8</sub>, calculated <i>A</i>(0) was approximately 10 meV/Å. With increasing temperature, <i>A</i>(<i>T</i>) exhibits a linear-like decrease and becomes approximately 7 meV/Å at around room temperature which is in the range of experimentally expected value. This behavior somewhat deviates from the theoretical prediction considering a magnon–magnon scattering in the Heisenberg model. For FePt, we found a considerable anisotropy between <i>A</i><sub>001</sub>(<i>T</i>) and <i>A</i><sub>100</sub>(<i>T</i>) for spiral wave vectors along the directions of 〈001〉 and 〈100〉, respectively.","PeriodicalId":17304,"journal":{"name":"Journal of the Physical Society of Japan","volume":"3 1","pages":""},"PeriodicalIF":1.7,"publicationDate":"2024-04-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140576441","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"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}
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