Nonlinear Pressure Dependence of the Curie Temperature in (Cr1-yVy)5Te8 and (Cr1-xTix)5Te8

概要

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It is known that Cr5Te8, V5Te8 and Ti5Te8 are ferromagnetic, weakly or nearly antiferromagnetic, and Pauli-paramagnetic materials, respectively. The temperature dependence of magnetization in (Cr1-yVy)5Te8 is measured, from which the magnetic phase diagram and the generalized Curie–Weiss (GCW) parameters are investigated. Gross feature of $\text{d}T_{\text{C}}$(Curie temperature)/d$y<0$ is similar to that of $\text{d}T_{\text{C}}/\text{d}x<0$ in (Cr1-xTix)5Te8, except $\text{d}T_{\text{C}}/dy \cong 0$ near $y=0$. No qualitative difference in the GCW parameters is observed in the low ranges of $y$ and $x$. The pressure ($P$) dependence of $T_{\text{C}}$ for the low ranges of $y$ and $x$ is investigated by measuring permeability. The observed nonlinear $P$-dependence of $T_{\text{C}}$ is systematically described with $T_{\text{C},P}=T_{\text{C},P=0} [1+{\zeta}P ] [1+{\eta}P ]^{2}$ for $\eta < 0$ and $\zeta > 0$ with $\text{d}\eta/\text{d}y < 0$, $\text{d}\eta/\text{d}x < 0$, $\text{d} \zeta/\text{d}y>0$ and $\text{d}\zeta/\text{d}x > 0$. The GCW, $T_{\text{C},P=0}$, $\eta$ and $\zeta$ parameters are connected to the spin fluctuation model for itinerant electron ferromagnetism proposed by Moriya. The obtained $y$ and $x$ dependence of GCW, $T_{\text{C},P=0}$, $\eta$ and $\zeta$ parameters is discussed on the view-point of the difference in electron correlation natures and magnetic states of Cr5Te8, V5Te8 and Ti5Te8.
2002-10-15