Magnetic and magnetocaloric properties of $\mathrm{HoCr}{\mathrm{O}}_3$ tuned by selective rare-earth doping

Journal Article · Thu May 18 00:00:00 EDT 2017 · Physical Review B

DOI:https://doi.org/10.1103/PhysRevB.95.184421· OSTI ID:1598171

Yin, Shiqi ^[1]; Seehra, Mohindar S. ^[2]; Guild, Curtis J. ^[1]; Suib, Steven L. ^[1]; Poudel, Narayan ^[3]; Lorenz, Bernd ^[3]; Jain, Menka ^[1]

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1. Univ. of Connecticut, Storrs, CT (United States)
2. West Virginia Univ., Morgantown, WV (United States)
3. Univ. of Houston, TX (United States)

Rare-earth chromites ( $R\mathrm{Cr}{\mathrm{O}}_3$) are an important subclass of functional materials with interesting magnetic, electrical, and catalytic properties that make them promising for various applications. In this paper, we report comparisons on the structural and magnetic properties of $\mathrm{HoCr}{\mathrm{O}}_3$ with those of $\mathrm{H}{\mathrm{o}}_{0.67}\mathrm{T}{\mathrm{m}}_{0.33}\mathrm{Cr}{\mathrm{O}}_3$ and $\mathrm{H}{\mathrm{o}}_{0.67}\mathrm{G}{\mathrm{d}}_{0.33}\mathrm{Cr}{\mathrm{O}}_3$ powder samples, which were doped by $\mathrm{T}{\mathrm{m}}^{3+}$ (or $\mathrm{G}{\mathrm{d}}^{3+}$) ions at the $A$-site with ionic radius smaller (or larger) than that of $\mathrm{H}{\mathrm{o}}^{3+}$ ion. The structural properties of the samples were characterized by x-ray diffraction, Raman spectroscopy, and scanning electron microscopy carried out at ambient. The band gaps of the three samples were determined by analyzing their ultraviolet Vis spectra. Magnetic studies carried out from 5 K to 300 K show that the Néel temperature ( $T_{\mathrm{N}}^{\mathrm{Cr}}$, where $\mathrm{C}{\mathrm{r}}^{3+}$ ions order) increases with an increase in the average $A$-site ( $R$-site) ionic radius, tolerance factor, and Cr1-O1-Cr1 bond angle but decreases with an increase in the orthorhombic strain factor. In addition, the application of external hydrostatic pressure was found to enhance $T_{\mathrm{N}}^{\mathrm{Cr}}$ of $\mathrm{HoCr}{\mathrm{O}}_3$, similar to the effect observed by doping $\mathrm{HoCr}{\mathrm{O}}_3$ with $\mathrm{G}{\mathrm{d}}^{3+}$ ions. These changes in $T_{\mathrm{N}}^{\mathrm{Cr}}$ with $A$-site doping and hydrostatic pressure are related to changes in $\mathrm{C}{\mathrm{r}}^{3+}-\mathrm{C}{\mathrm{r}}^{3+}$ exchange coupling resulting from changes in the Cr1-O1-Cr1 bond angle and Cr1-O1 bond lengths, respectively. Temperature dependent paramagnetic susceptibility data of the samples was fitted to the modified Curie-Weiss law that included the Dzyloshinskii-Moriya interaction. Isothermal magnetization data showed that the magnetic behavior of the samples changes from canted antiferromagnetic at low temperatures to paramagnetic at higher temperatures. The large magnetocaloric entropy change was observed in $\mathrm{HoCr}{\mathrm{O}}_3$, which was enhanced by Gd doping but lowered by Tm doping, showing its tunability by $A$-site doping. Correlation between magnetoelectric properties and magnetization is discussed.

• Research Organization: Univ. of Connecticut, Storrs, CT (United States)
• Sponsoring Organization: USDOE Office of Science (SC), Basic Energy Sciences (BES). Chemical Sciences, Geosciences, and Biosciences Division; National Science Foundation (NSF); US Air Force Office of Scientific Research (AFOSR)
• Grant/Contract Number: FG02-86ER13622; DMR-1310149; FA9550-09-1-0656
• OSTI ID: 1598171
• Alternate ID(s): OSTI ID: 1357849
• Journal Information: Physical Review B, Vol. 95, Issue 18; ISSN 2469-9950
• Publisher: American Physical Society (APS)
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
75 CONDENSED MATTER PHYSICS
SUPERCONDUCTIVITY AND SUPERFLUIDITY
Antiferromagnetism
Magnetic phase transitions
Magnetism
Magnetocaloric effect
Pressure effects