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Probing the quantum phase transition in Mott insulator BaCoS$$_{2}$$ tuned by pressure and Ni substitution

Guguchia, Z.*; Frandsen, B. A.*; Santos-Cottin, D.*; 社本 真一; Gauzzi, A.*; 植村 泰朋*; 他12名*

Physical Review Materials (Internet), 3(4), p.045001_1 - 045001_9, 2019/04

 被引用回数:1 パーセンタイル:100(Materials Science, Multidisciplinary)



Uniaxial pressure effect on the magnetic ordered moment and transition temperatures in BaFe$$_{2-x}$$T$$_{x}$$As$$_{2}$$ ($$T$$ = Co,Ni)

Tam, D. M.*; Song, Y.*; Man, H.*; Cheung, S. C.*; Yin, Z.*; Lu, X.*; Wang, W.*; Frandsen, B. A.*; Liu, L.*; Gong, Z.*; et al.

Physical Review B, 95(6), p.060505_1 - 060505_6, 2017/02

 被引用回数:15 パーセンタイル:23.77(Materials Science, Multidisciplinary)

We use neutron diffraction and muon spin relaxation to study the effect of in-plane uniaxial pressure on the antiferromagnetic (AF) orthorhombic phase in BaFe$$_{2-x}$$T$$_{x}$$As$$_{2}$$ and its Co- and Ni-substituted members near optimal superconductivity. In the low-temperature AF ordered state, uniaxial pressure necessary to detwin the orthorhombic crystals also increases the magnetic ordered moment, reaching an 11% increase under 40 MPa for BaFe$$_{1.9}$$Co$$_{0.1}$$As$$_2$$, and a 15% increase for BaFe$$_{1.915}$$Ni$$_{0.085}$$As$$_2$$. We also observe an increase of the AF ordering temperature ($$T_N$$) of about 0.25 K/MPa in all compounds, consistent with density functional theory calculations that reveal better Fermi surface nesting for itinerant electrons under uniaxial pressure. The doping dependence of the magnetic ordered moment is captured by combining dynamical mean field theory with density functional theory, suggesting that the pressure-induced moment increase near optimal superconductivity is closely related to quantum fluctuations and the nearby electronic nematic phase.


Volume-wise destruction of the antiferromagnetic Mott insulating state through quantum tuning

Frandsen, B. A.*; Liu, L.*; Cheung, S. C.*; Guguchia, Z.*; Khasanov, R.*; Morenzoni, E.*; Munsie, T. J. S.*; Hallas, A. M.*; Wilson, M. N.*; Cai, Y.*; et al.

Nature Communications (Internet), 7, p.12519_1 - 12519_8, 2016/08

 被引用回数:13 パーセンタイル:33.61(Multidisciplinary Sciences)

RENiO$$_3$$ (RE = rare-earth element) and V$$_2$$O$$_3$$ are archetypal Mott insulator systems. When tuned by chemical substitution (RENiO$$_3$$) or pressure (V$$_2$$O$$_3$$), they exhibit a quantum phase transition (QPT) between an antiferromagnetic Mott insulating state and a paramagnetic metallic state. Because novel physics often appears near a Mott QPT, the details of this transition, such as whether it is first or second order, are important. Here, we demonstrate through muon spin relaxation/rotation experiments that the QPT in RENiO$$_3$$ and V$$_2$$O$$_3$$ is first order: the magnetically ordered volume fraction decreases to zero at the QPT, resulting in a broad region of intrinsic phase separation, while the ordered magnetic moment retains its full value until it is suddenly destroyed at the QPT. These findings bring to light a surprising universality of the pressure-driven Mott transition, revealing the importance of phase separation and calling for further investigation into the nature of quantum fluctuations underlying the transition.


Diluted ferromagnetic semiconductor Li(Zn,Mn)P with decoupled charge and spin doping

Deng, Z.*; Zhao, K.*; Gu, B.; Han, W.*; Zhu, J. L.*; Wang, X. C.*; Li, X.*; Liu, Q. Q.*; Yu, R. C.*; 後神 達郎*; et al.

Physical Review B, 88(8), p.081203_1 - 081203_5, 2013/08

 被引用回数:60 パーセンタイル:6.82(Materials Science, Multidisciplinary)

We report the discovery of a diluted magnetic semiconductor, Li(Zn,Mn)P, in which charge and spin are introduced independently via lithium off-stoichiometry and the isovalent substitution of Mn$$^{2+}$$ for Zn$$^{2+}$$, respectively. Isostructural to (Ga,Mn)As, Li(Zn,Mn)P was found to be a ${it p}$-type ferromagnetic semiconductor with excess lithium providing charge doping. First-principles calculations indicate that excess Li is favored to partially occupy the Zn site, leading to hole doping. Ferromagnetism with Curie temperature up to 34 K is achieved while the system still shows semiconducting transport behavior.


Li(Zn,Mn)As as a new generation ferromagnet based on a I-II-V semiconductor

Deng, Z.*; Jin, C. Q.*; Liu, Q. Q.*; Wang, X. C.*; Zhu, J. L.*; Feng, S. M.*; Chen, L. C.*; Yu, R. C.*; Arguello, C.*; 後神 達郎*; et al.

Nature Communications (Internet), 2, p.1425_1 - 1425_5, 2011/08

 被引用回数:123 パーセンタイル:6.05(Multidisciplinary Sciences)



$$mu$$SR study of CeRhIn$$_5$$ under applied pressure

Heffner, R.*; 後神 達郎*; Andreica, D.*; 大石 一城*; 髭本 亘; 伊藤 孝; Amato, A.*; Spehling, J.*; Klauss, H. H.*; Bauer, E. D.*; et al.

Journal of Physics; Conference Series, 225, p.012011_1 - 012011_6, 2010/06

 被引用回数:1 パーセンタイル:45.64

At ambient pressure CeRhIn$$_5$$ is an incommensurate antiferromagnet with Neel temperature $$T_{rm N}$$ = 3.8 K. The application of pressure reduces $$T_{rm N}$$ and yields (1) a state in which AFM coexists with superconductivity, and then (2) a superconducting state in the absence of AFM. We report transverse-field muon spin relaxation ($$mu$$SR) measurements at pressures 2.07 and 2.26 GPa in the pure superconducting state of single-crystalline CeRhIn$$_5$$. $$mu$$SR is sensitive to the local field distribution produced by the vortex lattice in a mixed superconducting state, allowing a measurement of the magnetic field penetration depth $$lambda (T)$$. We measured $$lambda_{ab}(T)$$ for applied field along the $$c$$-axis as a function of temperature $$T$$, and find $$lambda_{ab}$$(0) = 372(5) nm and 338(6) nm for $$P$$ = 2.07 GPa and 2.26 GPa, respectively. The $$T$$-dependence of the superfluid density $$rho_s(T) propto lambda^{-2}(T)$$ was found to be $$rho_s(T) propto T^n$$ with $$n$$ = 1.9(2).


Muon spin rotation measurements of heterogeneous field response in overdoped La$$_{2-x}$$Sr$$_{x}$$CuO$$_{4}$$

MacDougall, G. J.*; Savici, A. T.*; Aczel, A. A.*; Birgeneau, R. J.*; Kim, H.*; Kim, S.-J.*; 伊藤 利充*; Rodriguez, J. A.*; Russo, P. L.*; 植村 泰朋*; et al.

Physical Review B, 81(1), p.014508_1 - 014508_7, 2010/01

 被引用回数:9 パーセンタイル:55.3(Materials Science, Multidisciplinary)

Transverse-field muon spin rotation measurements of overdoped La$$_{2-x}$$Sr$$_{x}$$CuO$$_{4}$$ reveal a large broadening of the local magnetic field distribution in response to applied field, persisting to high temperatures. The field response is approximately Curie-Weiss-like in temperature and is largest for the highest doping investigated. Such behavior is contrary to the canonical Fermi-liquid picture commonly associated with the overdoped cuprates and implies extensive heterogeneity in this region of the phase diagram. A possible explanation for the result lies in regions of staggered magnetization about dopant cations, analogous to what is argued to exist in underdoped systems.


Absence of broken time-reversal symmetry in the pseudogap state of the high temperature La$$_{2-x}$$Sr$$_{x}$$CuO$$_{4}$$ superconductor from muon-spin-relaxation measurements

MacDougall, G. J.*; Aczel, A. A.*; Carlo, J. P.*; 伊藤 利充*; Rodriguez, J.*; Russo, P. L.*; 植村 泰朋*; 脇本 秀一; Luke, G. M.*

Physical Review Letters, 101(1), p.017001_1 - 017001_4, 2008/07

 被引用回数:59 パーセンタイル:10.16(Physics, Multidisciplinary)



Muon spin rotation study of field-induced magnetism in heavily overdoped La$$_{2-x}$$Sr$$_{x}$$CuO$$_{4}$$

MacDougall, G. J.*; Birgeneau, R. J.*; Kim, H.*; Kim, S.-J.*; Rodriguez, J.*; Russo, P. L.*; Savici, A. T.*; 植村 泰朋*; 脇本 秀一; Wiebe, C. R.*; et al.

Physica B; Condensed Matter, 374-375, p.211 - 214, 2006/03

 被引用回数:4 パーセンタイル:75.64(Physics, Condensed Matter)

高温超伝導体の研究において、単結晶試料育成や化学的ドーピングの困難から、過剰ドープ領域の研究はほとんどなされていなかった。本研究では、世界初となる過剰ドープしたLa$$_{2-x}$$Sr$$_{x}$$CuO$$_{4}$$単結晶の$$mu$$SR実験の結果を報告する。縦磁場$$mu$$SRの結果から、relaxation rateの温度依存性がCurie-Weiss則に従い、そのCurie constantが磁場の関数として$$Cproptoalpha H$$と書かれることが見いだされた。この現象は、内部磁場分布の異常が磁場により誘起されていることを示している。磁場誘起の度合を表す$$alpha$$$$x=0.12$$から既に現れ、過剰ドープ領域の$$x=0.30$$まで単調増加し、ドープ量に依存することがわかった。この磁場誘起による異常な内部磁場分布の原因の解明は、今後の重要な課題である。

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