Effect of electric current on the Jahn–Teller distortion modes in La 0.67– y Pr y Ca 0.33 MnO 3

The sensitivity of transport and the lattice to a direct current has been investigated by means of in situ measurements of resistivity ϱ and Young's modulus E along with magnetic measurements in La 0.67– y Pr y Ca 0.33 MnO 3 ( y = 0, 0.15, 0.25, and 0.30) compounds. Increasing the Pr doping level enhances the softening of the magnitude of E with the appearance of a minimum in the curve of the temperature dependence of the modulus, E ( T ). The direct current depresses the resistivity and shifts the E ( T ) minimum to lower temperatures dramatically for the compounds with y ≥ 0.25, which exhibit a distinct magnetic hysteresis loop. The resistivity drop caused by the larger current may result from the depression of the Q 3 ‐type distortion mode of Mn 3+ O 6 octahedra by the current, which may favor the lower resistivity. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)