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Jiang, N.*; 新居 陽一*; 有沢 洋希*; 齊藤 英治; 大江 純一郎*; 小野瀬 佳文*
Physical Review Letters, 126(17), p.177205_1 - 177205_5, 2021/04
被引用回数：4 パーセンタイル：49.47(Physics, Multidisciplinary)Chirality in a helimagnetic structure is determined by the sense of magnetic moment rotation. We found that the chiral information did not disappear even after the phase transition to the high-temperature ferromagnetic phase in a helimagnet MnP. The 2nd harmonic resistivity 
, which reflects the breaking down of mirror symmetry, was found to be almost unchanged after heating the sample above the ferromagnetic transition temperature and cooling it back to the helimagnetic state. The application of a magnetic field along the easy axis in the ferromagnetic state quenched the chirality-induced . This indicates that the chirality memory effect originated from the ferromagnetic domain walls.
Jiang, N.*; 新居 陽一*; 有沢 洋希*; 齊藤 英治; 小野瀬 佳文*
Nature Communications (Internet), 11, p.1601_1 - 1601_6, 2020/03
被引用回数：27 パーセンタイル：85.73(Multidisciplinary Sciences)A helimagnet is a chiral magnet in which the direction of the magnetic moment spatially rotates in a plane perpendicular to the propagation vector. The sense of the rotation known as spin helicity is a robust degree of freedom of matter and may provide a new concept of magnetic memory if it can be electrically controlled and detected. Here we show that the helicity can be controlled by magnetic fields and electric currents in an itinerant helimagnet MnP. Second-harmonic resistivity measurements allow us to read out the controlled helicity. In contract to an insulating multiferroic magnet, in which spin rotation was shown to be controllable by an electric field, we achieve helicity manipulation by using an electric current in the conducting helimagnet. The controllability of the spin helicity may pave the way to new method of realizing magnetic memories based on the spin internal degrees of freedom.
with an 
= 3/2 antiferromagnetic triangular sublattice奥田 哲治*; 宇都 数馬*; 関 真一郎*; 小野瀬 佳文*; 十倉 好紀*; 梶本 亮一; 松田 雅昌*
Journal of the Physical Society of Japan, 80(1), p.014711_1 - 014711_7, 2011/04
被引用回数：26 パーセンタイル：76.24(Physics, Multidisciplinary)We investigated an effect of spin dilution on the magnetic and thermal properties of delafossite CuCrO having an = 3/2 antiferromagnetic triangular lattice (ATL) by the substitution of Al
for Cr by measurements of magnetization, specific heat, and neutron scattering. Spin defects introduced into Cr ATL layers blur the antiferromagnetic transition and induce a dimensional crossover of low-energy magnetic excitation in the residual Cr ATL region due to the reduction of inter-layer magnetic interaction, while accompanying an enhancement of a spin-glass component. The observed 
contribution to the low-
above 
= 0.15, as well as in Cu
Ag
CrO, comes mainly from a short-range 2D AF excitation originating in a nontrivial magnetic state such as spin-nematic or spin-liquid states.
Sr
VO
打田 正輝*; 大石 晃史*; 松尾 まり; 小椎八重 航*; 小野瀬 佳文*; 森 道康; 藤岡 淳*; 宮坂 茂樹*; 前川 禎通; 十倉 好紀*
Physical Review B, 83(16), p.165127_1 - 165127_5, 2011/04
被引用回数：30 パーセンタイル：74.51(Materials Science, Multidisciplinary)We report a systematic investigation on the high-temperature thermoelectric response in a typical filling-control Mott transition system LaSrVO. In the vicinity of the Mott transition, incoherent charge transport appears with increasing temperature and the thermopower undergoes two essential crossovers, asymptotically approaching the limit values expected from the entropy consideration, as known as Heikes formula. By comparison with the results of the dynamical mean field theory, we show that the thermopower in the Mott critical state mainly measures the entropy per charge carrier that depends on electronic degrees of freedom available at the measurement temperature. Our findings verify that the Heikes formula is indeed applicable to the real correlated electron systems at practical temperatures (T
200K).
武田 全康; 遠藤 康夫; 加倉井 和久; 小野瀬 佳文*; 鈴木 淳市; 十倉 好紀*
Journal of the Physical Society of Japan, 78(9), p.093704_1 - 093704_4, 2009/09
被引用回数：18 パーセンタイル：68.36(Physics, Multidisciplinary)Fe
Co
Siの長距離磁気秩序状態が示す複雑な磁気相転移の様子を低温,外部磁場下で中性子小角散乱によって調べた。リング状,三日月状,ぼやけた回折線など、温度と外部磁場によってさまざまな散乱パターンが現れた。この結果は、磁化を液晶の配向ベクトルとみなすことで、液晶で見られる相転移との類似性を明らかにした。
Ag
CrO with a spin-3/2 antiferromagnetic triangular sublattice奥田 哲治*; 岸本 泰造*; 宇都 数馬*; 外園 貴久*; 小野瀬 佳文*; 十倉 好紀*; 梶本 亮一; 松田 雅昌
Journal of the Physical Society of Japan, 78(1), p.013604_1 - 013604_4, 2009/01
被引用回数：26 パーセンタイル：75.72(Physics, Multidisciplinary)Dimensional crossover from anisotropic-3-dimensional (3D) to 2D low-energy magnetic excitations was found in delafossite oxide CuAgCrO having a spin-3/2 antiferromagnetic (AF) triangular lattice. The crossover is evidenced by a decrease in AF transition temperature (
), distinct 2D magnetic excitations above for CuAgCrO, a disappearance of a peak of magnetic specific heat () around , and a successive change from 
to 
dependence of low- accompanying a low- shift of magnetic entropy. These results may suggest a gradual change from AF to spin-liquid like states with an increase in 
.
武田 全康; 遠藤 康夫; 小野瀬 佳文*; 加倉井 和久; 鈴木 淳市; 十倉 好紀*
no journal, ,
強磁性金属FeCoSi(
)は、反対称相互作用による長距離らせん磁気秩序を示すが、対称性の低い(B20型)立方晶故にカイラル特性を示す。偏極中性子小角散乱による詳細な磁化過程の測定により磁区構造がもたらす磁気長距離秩序構造の詳細から磁気液晶相の相転移を明らかにした。
武田 全康; 遠藤 康夫; 小野瀬 佳文*; 加倉井 和久; 鈴木 淳市; 十倉 好紀*
no journal, ,
FeCoSiの長距離磁気秩序状態における複雑な相転移の様子を中性子小角散乱法によって調べた。その結果、外部磁場下において、長距離磁気秩序の磁区構造が液晶に似た振る舞いをすることを見いだした。温度や外部磁場を変えることにより、円環状,三日月状,散漫散乱を伴うスポット等のさまざまな小角散乱パターンを観測した。このような振る舞いは、外部磁場下でのコニカル状態が持つ磁気モーメントの強磁性成分を液晶のdirectorとみなすことで、液晶の総転移との類似性で説明することができる。
