Jahn–Teller transition and electron–phonon interaction in Cr-doped manganites Sr 0.9Ce 0.1Mn 1− yCr yO 3

Abstract

Cr-doped manganites Sr 0.9Ce 0.1Mn 1− y Cr y O 3 ( y=0, 0.05, and 0.10) have been systematically investigated by X-ray, magnetic, transport, and elastic properties measurements. For parent compound Sr 0.9Ce 0.1MnO 3, it undergoes a metal–insulator (M–I) transition at 318 K, which is suggested to originate from a first-order structural transition accompanied by Jahn–Teller (JT) transition. With increasing Cr doping content, the JT transition temperature decreases. The Cr doping suppresses the antiferromagnetic (AFM) state and makes the system spin-glass (SG) behavior at low temperatures. In the vicinity of JT transition temperatures, the softening of Young's modulus originating from the coupling of the orbital (quadrupolar) moment of the e g orbital of Mn 3+ ion to the elastic strain has been observed. The anomalous Young's modulus properties imply the electron–phonon coupling due to the JT effect may play an important role in the system.