Superconducting and normal-state interlayer exchange coupling inLa0.67Sr0.33MnO3−Y

Abstract

The issue of interlayer exchange coupling in magnetic multilayers with superconducting (SC) spacer is addressed in La0.67Sr0.33MnO3 (LSMO) -YBa2Cu3O7 (YBCO) -La0.67Sr0.33MnO3 (LSMO) epitaxial trilayers through resistivity, ac-susceptibility and magnetization measurements. The ferromagnetic (FM) LSMO layers possessing in-plane magnetization suppress the critical temperature (Tc) of the c-axis oriented YBCO thin film spacer. The superconducting order, however, survives even in very thin layers (thickness dY ∼ 50Å, ∼ 4 unit cells) at T < 25 K. A predominantly antiferromagnetic (AF) exchange coupling between the moments of the LSMO layers at fields < 200 Oe is seen in the normal as well as the superconducting states of the YBCO spacer. The exchange energy J1 (∼ 0.08 erg/cm 2 at 150 K for dY = 75Å) grows on cooling down to Tc, followed by truncation of this growth on entering the superconducting state. The coupling energy J1 at a fixed temperature drops exponentially with the thickness of the YBCO layer. The temperature and dY dependencies of this primarily non-oscillatory J1 are consistent with the coupling theories for systems in which transport is controlled by tunneling. The truncation of the monotonic T dependence of J1 below Tc suggests inhibition of single electron tunneling across the CuO2 planes as the in-plane gap parameter acquires a non-zero value.

Magnetization dynamics in La0.67Ca0.33MnO3 epitaxial films probed with resonant and non-resonant microwave absorption

“…In La 0.67 S r0.33 MnO 3 on the other hand, the paramagnetic state is metallic. 16 The resistivity reaches a peak value and then drops continuously down to the lowest temperature of measurement (5 K), marking a metallic behavior. The temperature at which the resistivity reaches the peak value below 300 K corresponds to the Curie temperature (T C ) of the material.…”

Spin-wave resonances inLa0.7Sr0.3MnO3films: Measurement of spin-wave stiffness and anisotropy field

“…Our experiments were performed with a bipolar X-band Bruker ESR spectrometer, a by the pulsed laser deposition [24] and were cut to small mm-size pieces in order to keep the reasonable value of the cavity Q-factor. We measured magnetization and resistivity of these films by SQUID magnetometry and four-point technique, correspondingly.…”

Crossover from magnetostatic to exchange coupling in La0.67Ca0.33MnO3/YBa2Cu3O7/La0.67Ca0.33MnO3heterostructures

“…F/S/F heterostructures (where F and S refer to ferromagnet and superconductor, respectively) have and continue to attract much attention due to the interesting physics arising from various couplings like proximity, magnetostatic, and exchange at the S/F interface [1][2][3][4].…”