High magnetic field properties in Ru 2 − x Fe x CrSi with antiferromagnetic and spin-glass states

We report experimental studies on ${\mathrm{Ru}}_{2\ensuremath{-}x}{\mathrm{Fe}}_{x}\mathrm{CrSi}$ focusing on properties related to antiferromagnetism in ${\mathrm{Ru}}_{2}\mathrm{CrSi}$ and spin glass (SG) in ${\mathrm{Ru}}_{1.9}{\mathrm{Fe}}_{0.1}\mathrm{CrSi}$. By measuring the temperature dependence of magnetization $M(T)$, specific heat $C(T)$, electrical resistivity $\ensuremath{\rho}(T)$, and muon spin relaxation ($\ensuremath{\mu}\mathrm{SR}$), we observed that ${\mathrm{Ru}}_{2}\mathrm{CrSi}$ exhibited an antiferromagnetic (AF) transition at a temperature ${T}_{N}$ of $\ensuremath{\sim}13$ K, and ${\mathrm{Ru}}_{1.9}{\mathrm{Fe}}_{0.1}\mathrm{CrSi}$ showed SG properties that could be interpreted as successive SG transitions, where the spin-freezing occurred at temperature ${T}_{g}$, and below that strong irreversibility in $M(T)$ and a gradual peak of $M(T)$ at ${T}^{*}\phantom{\rule{4pt}{0ex}}(g{T}_{g})$ appeared. When the data for $0\ensuremath{\le}x\ensuremath{\le}0.1$ were compared, by substituting Fe the AF order was rapidly destroyed and it appeared to change to two anomalies at ${T}^{*}$ and ${T}_{g}$. With increasing $x$, there was a slight change in ${T}_{g}$ from ${T}_{N}$ for $x=0$; however, ${T}^{*}$ increased, suggesting that the AF and the SG states are closely related. Furthermore, the results of specific heat, resistivity, and magnetization in high fields were presented and compared. For ${\mathrm{Ru}}_{2}\mathrm{CrSi}$ in specific heat under high magnetic fields up to 14 T, the peak shape around ${T}_{N}$ and the ${T}_{N}$ value were constant. The resistivity and magnetization in pulsed fields suggested that ${T}_{N}$ of ${\mathrm{Ru}}_{2}\mathrm{CrSi}$ was constant up to over 50 T. These results demonstrated the unusual robustness of the AF transition to magnetic fields. In ${\mathrm{Ru}}_{1.9}{\mathrm{Fe}}_{0.1}\mathrm{CrSi}$, unusual hysteresis in magnetoresistance was observed in static and pulsed magnetic fields, although their appearances differed. These hystereses were considered a manifestation of the curious properties of the SG state with strong irreversibility.