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

paper

Zigzag spin chains in the spin-5/2 antiferromagnet Ba $_{2}$ Mn(PO $_{4})_{2}$

arXiv:1804.02685

Abstract

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 $T_{N} ≃ 5$ \,K marks the onset of the antiferromagnetic order with the propagation vector $k = (\frac{1}{2} 0 \frac{1}{2})$ and ordered moment of $4.33 \pm 0.08 μ_{B}$ /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.

arXiv comment12 pages, 12 figures

Zigzag spin chains in the spin-5/2 antiferromagnet Ba2​Mn(PO4​)2​

Abstract

References in corpus (9)

Zigzag spin chains in the spin-5/2 antiferromagnet Ba $_{2}$ Mn(PO $_{4})_{2}$