Correlated negative magnetization, exchange bias, and electrical properties in La1−xPrxCrO3

Abstract

In the present work, we report the correlations among negative magnetization (NM), exchange bias (EB), and electrical properties in ${\mathrm{La}}_{1\text{\ensuremath{-}}x}{\mathrm{Pr}}_{x}{\mathrm{CrO}}_{3}$ $(x=0, 0.25, 0.5, 0.75, \mathrm{and} 1)$ compounds using dc magnetization, neutron depolarization, neutron diffraction, and impedance spectroscopy. The dc magnetization study infers the negative magnetization (NM) phenomenon in $x=0.25$, 0.5, and 0.75 compounds, where the compensation temperature $({T}_{\mathrm{COMP}})$ increases with $x$. At low temperature $(T<{T}_{\mathrm{COMP}})$, these compounds exhibit NM along with positive EB, indicating a correlation between the negative polarity of magnetization and the positive polarity of EB. However, the end compound $x=0$ does not show any NM and/or EB, whereas the other end compound, $x=1$, shows a negative EB without any NM. The presence or absence of magnetization reversal has been explained within the framework of Cooke's model which involves a competition between antiparallel coupled canted ${\mathrm{Cr}}^{3+}$ and polarized ${\mathrm{Pr}}^{3+}$ moments. Interestingly, maximum ac conductivity (with minimum activation energy required for conduction) at $x=0.75$ (which exhibits maximum ${T}_{\mathrm{COMP}}$) is found entangled with the lattice parameters' crossover from $a<c$ to $a>c$ around $x=0.75$, as evident from the neutron diffraction study. The physics behind the polarity reversals of magnetization and EB, and its close connection with electrical properties, has been understood by employing the macroscopic, mesoscopic, and microscopic experimental techniques. Such correlated physical properties make these compounds useful for making thermomagnetic switches and thermal-assisted magnetic random access memory.