Development of Spatial Inhomogeneity of Internal Magnetic Field Above T_c in Bi₂Sr₂Ca_1−xY_xCu₂O_8+δ Observed by Longitudinal-Field Muon Spin Relaxation

Abstract

Longitudinal-field muon-spin-relaxation measurements have revealed inhomogeneous distribution of the internal magnetic field at temperatures above the bulk superconducting (SC) transition temperature, T c , in slightly overdoped Bi 2 Sr 2 Ca 1−x Y x Cu 2 O 8+δ . The distribution width of the internal magnetic field, ∆, evolves continuously with decreasing temperature toward T c . The origin of the increase in ∆ is discussed in terms of the creation of SC domains in a sample.

Quasi-Static Internal Magnetic Field Detected in the Pseudogap Phase of Bi$_{2+x}$Sr$_{2-x}$CaCu$_2$O$_{8+δ}$ by $μ$SR

“…( 3) yields λ LF ≤ 3×10 −4 µs −1 , which is far smaller that the LF relaxation rates reported in Ref. [40] and well below the reliable detection limit. There is strong evidence for fluctuating SC domains in Bi2212 and Y123 well above T c from high transverse-field (TF) µSR experiments, which are highly sensitive to a distribution of time-averaged internal magnetic fields [44].…”

“…A previous weak LF-µSR study of overdoped polycrystalline samples of Bi 2 Sr 2 Ca 1−x Y x Cu 2 O 8+δ in a LF of 20 G revealed a small increasing relaxation rate below ∼ 135 K in a T c = 81 K sample [40]. While attributed to an inhomogeneous distribution of internal magnetic field generated by SC domains, the frequency scale for SC fluctuations above T c (10 10 to 10 14 Hz) established by other methods [41][42][43] is too high to produce an observable LF relaxation.…”

μSR Studies on Magnetism in High-Tc Cuprates

“…88) Besides, several μSR studies on the relation between the pseudogap and superconductivity or superconducting fluctuations have been reported. [89][90][91] 3.6 Ferromagnetism in the heavily overdoped regime of hole-doped cuprates As to the non-superconducting heavily overdoped regime of hole-doped high-T c cuprates as shown in Fig. 2, a theoretical study by Kopp et al 92) has predicted the existence of a ferromagnetic order at low temperatures.…”