Electronic and structural instabilities of single-crystalline La2-x-yNdySrxCuO4 near 1/8 doping

We have performed ultrasonic measurements, X-ray diffraction, resistivity and susceptibility measurements in order to investigate the correlation between the structural instability and the electronic states in the normal state of single-crystalline La2-x-yNdySrxCuO4 with x=1/8 and y=0.4. There exist two structural phase transitions at low temperatures, one of which is of the 2nd order (OMT-OLT) and the other is of the 1st order (OLT-TLT). The phase transition to the TLT phase appears to couple to the electronic instability leading to the local suppression of superconductivity.