Coupled spin–orbital–lattice anomalies in Y 0.7 La 0.3 VO 3 near the Néel transition: a phenomenological compressible ising-type analysis

A coupled compressible Ising-type phenomenological framework is developed for the thermodynamic, magnetic, orbital/distortive, and lattice responses of Y0.7La0.3VO3 near its Néel transition. The equilibrium relations retain explicit coupling terms, although the available data do not permit independent determination of the individual coupling coefficients. Simultaneous two-branch fitting of the lattice-subtracted heat capacity gives TN fit⁣= 114.9 K and αeff= -0.26 for the full analyzed range, corresponding to a finite cusp. The pronounced fit-range sensitivity of α_eff indicates that no range-independent asymptotic critical exponent or universality-class assignment can be established. Thermodynamic integration yields an entropy change consistent with the reported value without multiplicative rescaling. The background-subtracted (101) diffraction excess is described by an effective power-law form, while finite-field magnetization is treated as a distinct uniform and canted response. Overall, the observed anomalies are mutually consistent with a coupled spin–orbital–lattice response.