Spectacular Increase of Resistivity by Thermal Cycling under a Magnetic Field in Pr0.5Ca0.5Mn0.99Cr0.01O3

The resistivity of Pr0.5Ca0.5Mn0.99Cr0.01O3 under H=4 T shows unusual instability against thermal cycling between 250 and 5 K. The resistivity at 10 K change from 100 omegacm in the first cycle to more than 106 omegacm in the fifth cycle. However, magnetization decreases only by 1.2% between the first and the fifth cycles. The unusual enhancement of resistivity is suggested to be due to strain-induced localization of charge carriers