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A mean-field plus pairing model for atomic nuclei in the Fe region was studied using a finite-temperature quantum Monte-Carlo method. We present results for thermodynamical quantities such as the internal energy and the specific heat. These…

核理论 · 物理学 2008-11-26 S. Rombouts , K. Heyde , N. Jachowicz

The dynamics of magnetic moments in iron-chromium alloys with different levels of Cr clustering show unusual features resulting from the fact that even in a perfect body-centred cubic structure, magnetic moments experience geometric…

材料科学 · 物理学 2019-05-22 J. B. J. Chapman , S. L. Dudarev , P. -W. Ma

We examine the feasibility of a simple description of Mn ions in III-V diluted magnetic semiconductors (DMSs) in terms of two species (components), motivated by the expectation that the Mn-hole exchange couplings are widely distributed,…

无序系统与神经网络 · 物理学 2009-11-07 Malcolm P. Kennett , Mona Berciu , R. N. Bhatt

In the spirit of multi-scale modelling magnetization dynamics at elevated temperature is often simulated in terms of a spin model where the model parameters are derived from first principles. While these parameters are mostly assumed…

材料科学 · 物理学 2017-07-04 A. Deák , D. Hinzke , L. Szunyogh , U. Nowak

We have studied the effect of Fe addition on the structural and magnetic transitions in the magnetic shape memory alloy Ni-Mn-Ga by substituting systematically each atomic species by Fe. Calorimetric and AC susceptibility measurements have…

A new scenario of the mechanism of intriguing ferromagnetic properties in Mn-doped magnetic semiconductor (Ga,Mn)As is examined in detail. We find that magnetic features seen in zero-field cooled and field cooled magnetizations are not…

材料科学 · 物理学 2009-11-11 K. Hamaya , T. Koike , T. Taniyama , T. Fujii , Y. Kitamoto , Y. Yamazaki

The Hofstadter-Hubbard model captures the physics of strongly correlated electrons in an applied magnetic field, which is relevant to many recent experiments on Moir\'e materials. Few large-scale, numerically exact simulations exists for…

强关联电子 · 物理学 2022-08-16 Jixun K. Ding , Wen O. Wang , Brian Moritz , Yoni Schattner , Edwin W. Huang , Thomas P. Devereaux

Determinant Quantum Monte Carlo (DQMC) is used to study the effect of non-zero hopping t_f in the localized f-band of the periodic Anderson model (PAM) in two dimensions. The low temperature properties are determined in the plane of…

强关联电子 · 物理学 2015-07-03 Axel Euverte , Simone Chiesa , Richard T. Scalettar , George G. Batrouni

We present calculations of the exchange interactions and Curie temperatures in Cr-based pnictides and chalcogenides of the form CrX with X=As, Sb, S, Se and Te, and the mixed alloys CrAs$_{50}$X$_{50}$ with X=Sb, S, Se, and Te. The…

材料科学 · 物理学 2010-03-02 S. K. Bose , J. Kudrnovský

We describe magneto-, baro- and elastocaloric effects (MCEs, BCEs and eCEs) in materials which possess both discontinuous (first-order) and continuous (second-order) magnetic phase transitions. Our ab initio theory of the interacting…

材料科学 · 物理学 2020-06-03 Eduardo Mendive-Tapia , Julie B. Staunton

Element specific ultrafast demagnetization was studied in Fe$_{1-x}$Ni$_{x}$ alloys, covering the concentration range between $0.1<x<0.9$. For all compositions, we observe a delay in the onset of Ni demagnetization relative to the Fe…

First principles studies were performed in order to find out the possibility of inducing half-metallicity in Heusler Compound CoFeMnSb, by means of alloying it with 3d-transition metal elements. Proper alloying element is selected through…

材料科学 · 物理学 2019-05-15 Upendra Kumar , P. V. Sreenivasa Reddy , Satadeep Bhattacharjee , Seung-Cheol Lee

We investigate the emergence of ferromagnetism in the two-dimensional metal-halide CoBr$_2$, with a special focus on the role of electronic correlations. The calculated phonon spectrum shows that the system is thermodynamically stable…

强关联电子 · 物理学 2021-05-13 Hrishit Banerjee , Markus Aichhorn

The electronic structure and intrinsic magnetic properties of $\text{Fe}_2\text{AlB}_2$-related compounds and their alloys have been investigated using density functional theory. For $\text{Fe}_2\text{AlB}_2$, the crystallographic $a$ axis…

材料科学 · 物理学 2017-03-22 Liqin Ke , Bruce N. Harmon , Matthew J. Kramer

Magnetic and electric properties of the Hubbard model with binary alloy disorder are studied within the dynamical mean--field theory. A paramagnet--ferromagnet phase transition and a Mott--Hubbard metal--insulator transition are observed…

强关联电子 · 物理学 2009-11-10 Krzysztof Byczuk , Martin Ulmke

Dynamic magnetic features of a mixed ferro-ferrimagnetic ternary alloy in the form of AB$_p$C$_{1-p}$, especially. The effect of Hamiltonian parameters on the dynamic magnetic features of the system are investigated. For this aim, an…

材料科学 · 物理学 2019-07-04 Mehmet Bati , Mehmet Ertaş

The generalized Heusler compounds Mn2CoZ (Z = Al, Ga, In, Si, Ge, Sn, Sb) with the Hg2CuTi structure are of large interest due to their half-metallic ferrimagnetism. The complex magnetic interactions between the constituents are studied by…

材料科学 · 物理学 2011-03-07 Markus Meinert , Jan-Michael Schmalhorst , Günter Reiss

The microscopic origin of metamagnetism and metamagnetic transitions in strongly anisotropic antiferromagnets is investigated within a quantum mechanical theory of correlated electrons. To this end the Hubbard model with staggered…

强关联电子 · 物理学 2009-10-30 K. Held , M. Ulmke , N. Bl"umer , D. Vollhardt

While achieving high Curie temperatures (above room temperature) in diluted magnetic semiconductors remains a challenge in the case of well controlled homogeneous alloys, several systems characterized by a strongly inhomogeneous…

We derive ab inito exchange parameters for general non-collinear magnetic configurations, in terms of a multiple scattering formalism. We show that the general exchange formula has an anisotropic-like term even in the absence of spin-orbit…

材料科学 · 物理学 2013-05-08 A. Szilva , M. Costa , A. Bergman , L. Szunyogh , L. Nordström , O. Eriksson