Jingsheng Zhu

Growth, structural characteristics and magnetoresistance in LaCaMnO thin films prepared by dc magnetron sputtering

Abstract Colossal magnetoresistive (CMR) La Ca Mn O thin films have been successfully fabricated by dc magnetron sputtering technique onto heated single crystal substrates such as LaAlO3(001) (LAO), SrTiO3(001) (STO), NdGaO3(110) (NGO) and ZrO2(001) (ZRO). The X-ray diffraction (XRD) patterns showed that the films deposited on LAO, STO and NGO substrates grow epitaxially (00l) with FWHM (δW) less than 0.5° due to excellent lattice matching and compatible coefficients of thermal expansion between the substrate and the thin film. Those deposited on ZRO preferred to grow (00l) texture orientation due to large mismatching of their lattice constants, and δW is about 10°. The magnetoresistance measurements show that all of these films exhibit remarkable CMR effect, but the temperature dependence of magnetoresistance in LCMO thin films strongly depend on substrates. These differences are associated with the different temperature dependence of magnetization due to their intrinsic structural characteristics.

The power-law magnetic-field-dependence of the giant magnetoresistance ratio in thin film

The temperature- and magnetic-field-dependences of the resistance in giant magnetoresistance (GMR) (LCMO) thin films have been studied. It is found that the magnetoresistance ratio can be expressed as near the ferromagnetic transition temperature when H<3 T. The temperature-dependence of is determined by A(T) and the exponent below 60 K and above 80 K. Under certain conditions, this kind of power-law magnetic-field-dependence of in LCMO thin film is similar to that in metallic magnetic multilayer or grain-type GMR thin films.

A phenomenological description of temperature dependence of magnetoresistance in La2/3Ca1/3MnO3-δ thin films

AbstractThe electrical resistance in zero magnetic field and magnetoresistance in different external magnetic fields have been measured in a temperature range of 77—300 K. It is found that the temperature dependence of magnetoresistance can be well described by a phenomenofogical formula of

The critical magnetic field in the high-Tc superconductive thin films

\rho (T) = \frac{1}{{\sigma (T)}} = \frac{1}{{(M/M_s )^2 + \beta ( - E_0 /k_B T)}}

Field dependence of magnetoresistance in epitaxial single-crystal La2/3Ca1/3MnO3-δ thin film

where the fitting parameters α, β vary as the external magnetic fieldH changes,E0 is the activation energy,E0/kB = 1160 K,Ms is the saturation magnetization, the temperature and magnetic field dependence ofM/Ms is obtained by the mean-field expression.

Preparation, structure, magnetic properties and special magnetoresistance effect of Lao.67Sr0.33Mn03+δ/Pr0.7Cao.3 Mn03+δ/Lao.67Sro.33Mn03+δ trilayered thin films

THE colossal magnetoresistance (CMR) effects in doped perovskite-like oxide have stimulatedconsiderable attention to the study of fundamental physics and the application of new type ma-terials. It was reported that a large CMR effect and a high critical temperature T c shown in...

Crystal growth and physical properties of ternary bismuth molybdenum oxides BixMoOy (x=0.21, 0.25; y=3 + δ)

Abstract In this paper, the analytical solution of the G-L equation applied to superconductive thin films in which κ ≫ 1 is given for the first time. The new - M ∼ H a , H cf ∼ d elationships are established.

Occurrence of metallic bismuth in Bi2Sr2CuOx crystals irradiated by N+ ions

Abstract Samples of Bi 2 Sr 2 CuO 6+χ , Bi 2 Sr 2 CaCu 2 O 8+ y and Bi 2.4− z Pb z Sr 2 CaCu 2 O 8+ w crystals have been irradiated by 648 KGy γ-rays parallel to the c -axis of the crystals. After irradiation the valence states of bismuth and copper shift to high binding energies. Also, new higher valence states occur in Bi 2 Sr 2 CaCu 2 O 8+ y and Bi 2.4− z Pb z Sr 2 CaCu 2 O 8+ w crystals, lead ding to a change in T c .