Magnetic microphase inhomogeneity as a thermodynamic precursor of ground-state phase separation in weakly coupled spin- 32 chains

Abstract

γ-CoV2O6 is a quasi one-dimensional spin-3 2 magnet that possesses two distinct magnetic orders in the ground state with modulation vectors k1 = ( 1 2 , 0, 0) and k2 = ( 1 4 , 0, -1 4 ), respectively. Here, we use muon spin relaxation and rotation to reveal the thermodynamics of the magnetic phase separation in this compound. In the paramagnetic (PM) region, short-range correlated spin clusters emerge at Tm 26 K at the partial expense of the PM volume. Upon further cooling, we show that these emergent clusters become spatially coherent at TN2 = 7.5 K and eventually form the k2 order at T = 5.6 K, while the remaining PM spins are driven into the k1 state at TN1 = 6.6 K. These results stress magnetic microphase inhomogeneity as a thermodynamic precursor for the ground state phase separation in weakly coupled spin-3 2 chains.