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Damping and Softening of Transverse Acoustic Phonons in Colossal Magnetoresistive La0.7Cad0.3^MnO3 and La0.7Sr0.3MnO3



Joel Helton, Yang Zhao, Dmitry A. Shulyatev, Jeffrey W. Lynn


Neutron spectroscopy is used to probe transverse acoustic phonons near the (2,2,0) Bragg position in colossal magnetoresistive La0.7Ca0.3MnO3. Upon warming to temperatures near Τc= 257 K the phonon peaks soften and damp and a quasielastic component develops that dominates the spectrum near the polaron position at high temperatures. This quasielastic scattering is {approximately equal} 5 times more intense near Τc than in the related compound La0.6Sr0.3MnO3 despite comparable structural distortions in the two. The damping becomes more significant near the polaron position with a temperature dependence similar to that of polaron structural distortions. An applied magnetic field of 9.5 T only partially reverses the damping and quasielastic component, despite smaller fields being sufficient to drive the colossal magnetoresistive effect. The phonon energy, on the other hand, is unaffected by field.
Physical Review B


colossal magnetoresistance, phonons, polarons


, J. , , Y. , , D. and , J. (2019), Damping and Softening of Transverse Acoustic Phonons in Colossal Magnetoresistive La<sub>0.7Ca</sub>d0.3^MnO<sub>3</sub> and La<sub>0.7</sub>Sr<sub>0.3</sub>MnO<sub>3</sub>, Physical Review B, [online], (Accessed April 17, 2024)
Created January 7, 2019, Updated October 9, 2019