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arXiv 1804.02685cond-mat.str-el
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自旋为5/2的反铁磁体$_2$ Mn(PO $_4)_2$)中的曲折自旋链

Zigzag spin chains in the spin-5/2 antiferromagnet Ba$_2$Mn(PO$_4)_2$

Arvind Yogi, A. K. Bera, Ashwin Mohan, Ruta Kulkarni, S. M. Yusuf, A. Hoser, A. A. Tsirlin, A. Thamizhavel

摘要:

基于中子衍射、密度泛函能带结构计算以及与温度和场相关的磁化强度和比热测量,报道了Ba $_{2}$ Mn(PO $_{4}$)$_{2}$反铁磁体的磁性和磁结构,该反铁磁体具有$S=\frac{5}{2}$ Mn $^{2+}$离子的阻挫之字形链.在$T_N\simeq 5$ \,K处的磁性转变标志着反铁磁序的开始,其中传播矢量${\mathbf k} = (\frac12\, 0\, \frac12)$和$4.33\pm0.08~μ_B$ /Mn $^{2+}$的有序矩在1.5\,K处指向$c$方向。磁矩的方向由单离子各向异性选择,其与同构Ni $^{2+}$化合物相比相对较弱。几何阻挫对Ba $_2$ Mn(PO $_4)_2$)的热力学性质有很大的影响,但阻挫的表现形式与Ba $_2$ Ni(PO $_4)_2$)不同,在Ba $_2$ Ni(PO)中,各向同性交换耦合的阻挫很小,但存在强的竞争性单离子各向异性.在2.5T附近观察到自旋翻转跃迁。从基态通过自旋翻转状态的场极化铁磁状态的磁结构的评价已被揭示作为一个功能的磁场低于$T_N$的一个全面的中子衍射研究。最后,在$H-T$平面的磁相图。

英文摘要:

Magnetic properties and magnetic structure of the Ba$_{2}$Mn(PO$_{4}$)$_{2}$ antiferromagnet featuring frustrated zigzag chains of $S=\frac{5}{2}$ Mn$^{2+}$ ions are reported based on neutron diffraction, density-functional band-structure calculations, as well as temperature- and field-dependent measurements of the magnetization and specific heat. A magnetic transition at $T_N\simeq 5$\,K marks the onset of the antiferromagnetic order with the propagation vector ${\mathbf k} = (\frac12\, 0\, \frac12)$ and ordered moment of $4.33\pm0.08~μ_B$/Mn$^{2+}$ at 1.5\,K, pointing along the $c$ direction. Direction of the magnetic moment is chosen by the single-ion anisotropy, which is relatively weak compared to the isostructural Ni$^{2+}$ compound. Geometrical frustration has strong impact on thermodynamic properties of Ba$_2$Mn(PO$_4)_2$, but manifestations of the frustration are different from those in Ba$_2$Ni(PO$_4)_2$, where frustration by isotropic exchange couplings is minor, yet strong and competing single-ion anisotropies are present. A spin-flop transition is observed around 2.5\,T. The evaluation of the magnetic structure from the ground state via the spin-flop state to the field-polarized ferromagnetic state has been revealed by a comprehensive neutron diffraction study as a function of magnetic field below $T_N$. Finally, a magnetic phase diagram in the $H-T$ plane is obtained.

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

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