Bi-collinear antiferromagnetic order in the tetragonal $α$-FeTe

First principles study of the structural phase stability and magnetic order in various structural phases of Mn$_2$FeGa

We investigate the structural and magnetic properties of Mn$_{2}$FeGa for different phases(cubic, hexagonal and tetragonal) reported experimentally using density functional theory. The relative structural stabilities, and the possible phase transformation mechanisms are discussed using results for total energy, electronic structure and elastic constants. We find that the phase transformation form hexagonal to ground state tetragonal structure would take place through a Heusler-like phase which has a pronounced electronic instability. The electronic structures, the elastic constants and the sup…

Pressure- and temperature-induced structural phase transitions of CaFe$_2$As$_2$ and BaFe$_2$As$_2$ studied in the Hund's rule correlation picture

With the proposed Hund's rule correlation picture, i.e. the fluctuating Fe local moments with the As-bridged antiferromagnetic superexchange interactions, the exceptional collapsed tetragonal phase and related phase transitions observed in CaFe$_2$As$_2$ are well understood. With the same framework, a pressure-temperature phase diagram is predicted for BaFe$_2$As$_2$ as well, in which a paramagnetic tetragonal and a collinear antiferromagnetic orthorhombic structures to nonmagnetic tetragonal structure transitions take place around 4-8 GPa and 10-15 GPa respectively, and a nonmagnetic tetragon…

Tetragonal phase of epitaxial room-temperature antiferromagnet CuMnAs

Recent studies have demonstrated the potential of antiferromagnets as the active component in spintronic devices. This is in contrast to their current passive role as pinning layers in hard disk read heads and magnetic memories. Here we report the epitaxial growth of a new high-temperature antiferromagnetic material, tetragonal CuMnAs, which exhibits excellent crystal quality, chemical order and compatibility with existing semiconductor technologies. We demonstrate its growth on the III-V semiconductors GaAs and GaP, and show that the structure is also lattice matched to Si. Neutron diffractio…

Structural, magnetic, and electrical properties of collinear antiferromagnetic heteroepitaxy cubic Mn$_3$Ga thin films

Although a cubic phase of Mn$_3$Ga with an antiferromagnetic order has been theoretically predicted, it has not been experimentally verified in a bulk or film form. Here, we report the structural, magnetic, and electrical properties of antiferromagnetic cubic Mn$_3$Ga (C-Mn$_3$Ga) thin films, in comparison with ferrimagnetic tetragonal Mn$_3$Ga (T-Mn3Ga). The structural analyses reveal that C-Mn$_3$Ga is hetero-epitaxially grown on MgO substrate with the Cu$_3$Au-type cubic structure, which transforms to T-Mn$_3$Ga as the RF sputtering power increases. The magnetic and magnetotransport data sh…

Predicting the Spin-Lattice Order of Frustrated Systems from First-Principles

A novel general method of describing the spin-lattice interactions in magnetic solids was proposed in terms of first principles calculations. The spin exchange and Dzyaloshinskii-Moriya interactions as well as their derivatives with respect to atomic displacements can be evaluated efficiently on the basis of density functional calculations for four ordered spin states. By taking into consideration the spin-spin interactions, the phonons, and the coupling between them, we show that the ground state structure of a representative spin-frustrated spinel, MgCr2 O4, is tetragonally distorted, in agr…

正交形变促成 CePdAl$_3$ 中的长程磁有序

Long-range magnetic order in CePdAl$_3$ enabled by orthorhombic deformation

本研究结合衍射、中子谱学与密度泛函计算，揭示 CePdAl$_3$ 的正交形变如何解除四方相中的反铁磁阻挫，并在 5.29(5) K 以下形成共线反铁磁长程有序。

Antiferromagnetic ground state with pair-checkboard order in FeSe

Monolayer FeSe thin film grown on SrTiO_{3}(001) (STO) shows the sign of T_{c}> 77 K, which is higher than the T_{c}-record of 56 K for the bulk FeAs-based superconductors. However, little is known about the magnetic ground state of FeSe, which should be closely related to its unusual superconductivity. Previous studies presume the collinear stripe antiferromagnetic (AFM) state as the ground state of FeSe, same to that in FeAs superconductors. Here we find a novel magnetic order named "pair-checkboard AFM" as the magnetic ground state of tetragonal FeSe. The novel pair-checkboard order results…