High-temperature magnetism and crystallography of a<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:msub><mml:mi>YCrO</mml:mi><mml:mn>3</mml:mn></mml:msub></mml:math>single crystal
Yinghao Zhu, Si Wu, Bao Tu, Shangjian Jin, Ashfia Huq, J. Perßon, Haoshi Gao, Defang Ouyang, Zhubing He, Dao‐Xin Yao, Zikang Tang, Haifeng Li
Abstract
Magnetization measurements and time-of-flight neutron powder-diffraction studies on the high-temperature (300--980 K) magnetism and crystal structure (321--1200 K) of a pulverized ${\mathrm{YCrO}}_{3}$ single crystal have been performed. Temperature-dependent inverse magnetic susceptibility coincides with a piecewise linear function with five regimes, with which we fit a Curie-Weiss law and calculate the frustration factor $f$. The fit results indicate a formation of magnetic polarons between 300 and 540 K and a very strong magnetic frustration. By including one factor $\ensuremath{\eta}$ that represents the degree of spin interactions into the Brillouin function, we can fit well the applied-magnetic-field dependence of magnetization. No structural phase transition was observed from 321 to 1200 K. The average thermal expansions of lattice configurations ($a$, $b$, $c$, and V) obey well the $\mathrm{Gr}\stackrel{\ifmmode \ddot{}\else \"{}\fi{}}{\mathtt{u}}\mathrm{neisen}$ approximations with an anomaly appearing around 900 K, implying an isosymmetric structural phase transition, and display an anisotropic character along the crystallographic $a$, $b$, and $c$ axes with the incompressibility ${K}_{0}^{a}>{K}_{0}^{c}>{K}_{0}^{b}$. It is interesting to find that at 321 K, the local distortion size $\mathrm{\ensuremath{\Delta}}$(O2) $\ensuremath{\approx}1.96\mathrm{\ensuremath{\Delta}}$(O1) $\ensuremath{\approx}4.32\mathrm{\ensuremath{\Delta}}$(Y) $\ensuremath{\approx}293.89\mathrm{\ensuremath{\Delta}}$(Cr). Based on the refined Y-O and Cr-O bond lengths, we deduce the local distortion environments and modes of Y, Cr, O1, and O2 ions. Especially, the Y and O2 ions display obvious atomic displacement and charge subduction, which may shed light on the dielectric property of the ${\mathrm{YCrO}}_{3}$ compound. Additionally, by comparing Kramers ${\mathrm{Mn}}^{3+}$ with non-Kramers ${\mathrm{Cr}}^{3+}$ ions, it is noted that being a Kramers or non-Kramers ion can strongly affect the local distortion size, whereas, it may not be able to change the detailed distortion mode.