Weickert, F., Harrison, N., Scott, B. L., Jaime, M., Leitmäe, A., Heinmaa, I., Stern, R., Janson, O., Berger, H., Rosner, H., & Tsirlin, A. A. (2016). Magnetic anisotropy in the frustrated spin-chain compound β-TeVO₄. Physical Review B, 94(6), Article 064403. https://doi.org/10.1103/physrevb.94.064403
Isotropic and anisotropic magnetic behavior of the frustrated spin-chain compound beta-TeVO 4 is reported. Three magnetic transitions observed in zero magnetic field are tracked in fields applied along different crystallographic directions using magnetization, heat capacity, and magnetostriction measurements. Qualitatively different temperature-field diagrams are obtained below 10 T for the field applied along a or b and along c, respectively. In contrast, a nearly isotropic high-field phase emerges above 18 T and persists up to the saturation that occurs around 22.5 T. Upon cooling in low fields, the transitions at T N1 and T N2 toward the spin-density-wave and stripe phases are of the second order, whereas the transition at TN3 toward the helical state is of the first order
and entails a lattice component. Our microscopic analysis identifies frustrated J1-J2 spin chains with a sizable antiferromagnetic interchain coupling in the bc plane and ferromagnetic couplings along the a direction. The competition between these ferromagnetic interchain couplings and the helical order within the chain underlies
the incommensurate order along the a direction, as observed experimentally. While a helical state is triggered by the competition between J1 and J2 within the chain, the plane of the helix is not uniquely defined because of competing magnetic anisotropies. Using high-resolution synchrotron diffraction and 125 Te nuclear magnetic resonance, we also demonstrate that the crystal structure of beta-TeVO4 does not change down to 10 K, and the orbital state of V4+ is preserved.
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Research Areas:
Computational Materials Science: 80% Quantum Modelling and Simulation: 20%