Effect of magnetic field on the charge-stripe phase in La2−x−yNdySrxCuO4: An ultrasonic attenuation study

We have studied the effect of a magnetic field on the charge-stripe phase in La1.48Nd0.4Sr0.12CuO4 and La2−xSrxCuO4 (x = 0.04, 0.12) by ultrasonic attenuation measurements. For La1.48Nd0.4Sr0.12CuO4, a magnetic field of 14 T has been found to have no essential influence on the attenuation peak around 70 K, which is associated with the formation of static charge stripes, and on the anomalous increase in the sound velocity below this temperature either, indicating that the static stripe order is very stable. For La1.88Sr0.12CuO4, the attenuation peak and the accompanying increase in sound velocity, which are located below the superconducting transition temperature, are shifted toward high temperature with increasing magnetic field, and simultaneously the increase in sound velocity is enhanced. The results indicate that an applied magnetic field can stabilize the charge stripes in La1.88Sr0.12CuO4. These measurements provide further evidence for the competition between superconductivity and charge-stripe order. In La1.48Nd0.4Sr0.12CuO4, the static stripe order is very stable while in La1.88Sr0.12CuO4 the stripe order is suppressed by superconductivity. With increasing magnetic field, the superconductivity is suppressed gradually and thus the charge-stripe order emerges. Measurements on La1.96Sr0.04CuO4 suggest that the magnetic field does not affect the charge stripes in the non-superconducting state.