Unconventional magnetic phase separation in ${\hat{I}}^3$-CoV${}_2$O${}_6$

Abstract

We have explored the magnetism in the non-geometrically frustrated spin-chain system ${\hat{I}}^3$-CoV${}_2$O${}_6$ which possesses a complex magnetic exchange network. Our neutron diffraction patterns at low temperatures ($T$ $⩽$ $T_{\mathrm{N}}$ = 6.6 K) are best described by a model in which two magnetic phases coexist in a volume ratio 65(1) : 35(1), with each phase consisting of a single spin modulation. This model fits previous studies and our observations better than the model proposed by Lenertz $et$ $al$ in J. Phys. Chem. C 118, 13981 (2014), which consisted of one phase with two spin modulations. By decreasing the temperature from $T_{\mathrm{N}}$, the minority phase of our model undergoes an incommensurate-commensurate lock-in transition at $T^{\ast }$ = 5.6 K. Based on these results, we propose that phase separation is an alternative approach for degeneracy-lifting in frustrated magnets.