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arXiv · 1303.5599

Magnetic phase diagrams, domain switching and a quantum phase transition of the quasi-1D Ising-like antiferromagnet BaCo2V2O8

S. K. Niesen·G. Kolland·M. Seher·O. Breunig·M. Valldor·M. Braden·B. Grenier·T. Lorenz
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Abstract

In the effective Ising spin-1/2 antiferromagnetic chain system BaCo$_2$V$_2$O$_8, the magnetic-field influence is highly anisotropic. For magnetic fields along the easy axis $c$, the N\'{e}el order is strongly suppressed already for low fields and an incommensurate order is entered above 4 T. We present a detailed study of the magnetic phase diagrams for different magnetic field directions, which are derived from magnetization data, high-resolution thermal expansion and magnetostriction measurements as well as from the thermal conductivity. Zero-field thermal expansion data reveal that the magnetic transition is accompanied by an orthorhombic distortion within the $ab$ plane. Under ambient conditions the crystals are heavily twinned, but the domain orientation can be influenced either by applying uniaxial pressure or a magnetic field along the [100] direction. In addition, our data reveal a pronounced in-plane magnetic anisotropy for fields applied within the $ab$ plane. For $H || [110]$, the magnetic field influence on T$_N$ is weak, whereas for magnetic fields applied along [100], T$_N$ vanishes at about 10 T and the zero-field N\'{e}el order is completely suppressed as is confirmed by neutron diffraction data. The second-order phase transition strongly suggests a quantum critical point being present at $H\simeq 10$ T parallel [100], where the N\'{e}el order probably changes to a spin-liquid state.

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S. K. Niesen, G. Kolland, M. Seher, O. Breunig, M. Valldor, M. Braden, B. Grenier, T. Lorenz. 2013-03-22. Magnetic phase diagrams, domain switching and a quantum phase transition of the quasi-1D Ising-like antiferromagnet BaCo2V2O8. https://doi.org/10.1103/physrevb.87.224413

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