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We report a heat switch effect in single crystals of an antiferromagnet Co$_3$V$_2$O$_8$, that is, the thermal conductivity ($kappa$) can be changed with magnetic field in an extremely large scale. Due to successive magnetic phase transitions at 12--6 K, the zero-field $kappa(T)$ displays a deep minimum at 6.7 K and rather small magnitude at low temperatures. Both the temperature and field dependencies of $kappa$ demonstrate that the phonons are strongly scattered at the regime of magnetic phase transitions. Magnetic field can suppress magnetic scattering effect and significantly recover the phonon thermal conductivity. In particular, a 14 T field along the $a$ axis increases the $kappa$ at 7.5 K up to 100 times. For $H parallel c$, the magnitude of $kappa$ can be suppressed down to $sim$ 8% at some field-induced transition and can be enhanced up to 20 times at 14 T. The present results demonstrate that it is possible to design a kind of heat switch in the family of magnetic materials.
We present macroscopic and neutron diffraction data on multiferroic lightly Co-doped Ni$_3$V$_2$O$_8$. Doping Co into the parent compound suppresses the sequence of four magnetic phase transitions and only two magnetically ordered phases, the paraele
Large single crystals of the new compound SrMn$_2$V$_2$O$_8$ have been grown by the floating-zone method. This transition-metal based oxide is isostructural to SrNi$_2$V$_2$O$_8$, described by the tetragonal space group $I4_1cd$. Magnetic properties
Since the seminal ideas of Berezinskii, Kosterlitz and Thouless, topological excitations are at the heart of our understanding of a whole novel class of phase transitions. In most of the cases, those transitions are controlled by a single type of top
Theoretical studies have predicted the existence of topological magnons in honeycomb compounds with zig-zag antiferromagnetic (AFM) order. Here we report the discovery of zig-zag AFM order in the layered and non-centrosymmetric honeycomb nickelate Ni
We use a combination of optical spectra, first principles calculations, and energy dependent magneto-optical measurements to elucidate the electronic structure and to study the phase diagram of Ni$_3$V$_2$O$_8$. We find a remarkable interplay of magn