μSRμSR study of magnetic order in La2-xBaxCuO4La2-xBaxCuO4 under high pressure

We have performed muon spin relaxation (μμSR) and resistivity measurements under high pressure in La2-xBaxCuO4La2-xBaxCuO4 with x=0.125x=0.125 and 0.135. With increasing pressure, the superconducting critical temperature TcTc increases for both samples. We estimate the low-temperature tetragonal (LTT) to the low-temperature orthorhombic (LTO) phase transition pressure PdPd from the pressure dependence of TcTc. Even by applying pressure above PdPd, static magnetic order still exists. This result indicates the LTT structure is not always necessary for stabilizing the static magnetic order. However, the magnetic volume fraction estimated from the amplitude of the oscillation component in the μμSR spectra is reduced by applying pressure. The reduction of the magnetic volume fraction for x=0.125x=0.125 is less than that for x=0.135x=0.135. This means hole concentration of 18 per Cu is one of the important factors for the appearance of the static magnetic order.