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Spin Frustration in Protonated Rutile Oxides.

Authors :: Kazuki Takaoka
Morito Namba
Haobo Li
Kodai Ishida
Hiroshi Takatsu
Hiroshi Kageyama
Source :: Journal of the Physical Society of Japan; 8/15/2021, Vol. 90 Issue 8, p1-5, 5p
Publication Year :: 2021
Abstract: We report the topochemical protonation of rutile oxides Rh<subscript>0.5</subscript>V<subscript>0.5</subscript>O<subscript>2</subscript> and Cr<subscript>0.5</subscript>V<subscript>0.5</subscript>O<subscript>2</subscript> by low-temperature hydrogen gas treatment. After the treatment, nonmagnetic V<superscript>5+</superscript> (d<superscript>0</superscript>) ions were selectively reduced to +3.5 (d<superscript>1.5</superscript>) for H<subscript>x</subscript>Rh<subscript>0.5</subscript>V<subscript>0.5</subscript>O<subscript>2</subscript> (x ~ 0.75) and +4 (d¹) for H<subscript>x</subscript>Cr<subscript>0.5</subscript>V<subscript>0.5</subscript>O<subscript>2</subscript> (x ~ <subscript>0.5</subscript>). H<subscript>x</subscript>Rh<subscript>0.5</subscript>V<subscript>0.5</subscript>O<subscript>2</subscript> with nonmagnetic Rh3+ ions has weak magnetic interactions with a spin glass transition at Tf = 6 K. In contrast, protonation of Cr<subscript>0.5</subscript>V<subscript>0.5</subscript>O<subscript>2</subscript> with Cr<superscript>3+</superscript> (d³) enhances antiferromagnetic interactions with the Weiss temperature of θ = -199(1) K. However, the spin glass transition temperature is still low (T<subscript>f</subscript> = 10 K), indicating competing interactions, in which a frustration factor of 20 is the largest among rutile compounds. Topochemical protonation can be a useful method for extending the family of magnetic oxides. [ABSTRACT FROM AUTHOR]