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Single crystals of Fe2(TeO3)2(SO4)·3H2O with an alternating spin-chain structure are successfully grown by a hydrothermal method. Magnetic and heat capacity measurements show that this compound possesses a short-range antiferromagetic order at ~55 K and a long-range antiferromagetic order at 32.5 K. A large magnetic anisotropy with magnetization easy c-axis is observed, in which a weak ferromagnetic component is observed along the a- and b-axes, while a spin flop transition is observed at applied field along the c-axis. Also, the magnetic anisotropy energy at 2 K is estimated to be 4.78(3) × 108 ergs/cm3. Such magnetic anisotropy may be due to a strong nonsymmetric distortion in the FeO6 octahedra.

The resistance of polycrystalline divalent-ion-doped LaMnO 3 has been shown to be highly sensitive to low magnetic fields. To enable direct study of the properties of isolated grain boundaries, we developed a new method to form artificial boundaries in manganite thin films. Metal slits about 70 nm in width were printed by 30 KV focused Ga ion beam nanolithography on a 4 μ m La 2 / 3 Sr 1 / 3 MnO 3 bridge, and the materials in these slits were then irradiated by accelerated H 2 + ions. Using this method, magnetoresistance (MR) > 8 % and > 16 % were, respectively, obtained at 150 and at 10 K in a magnetic field of 1 T. This technique is very promising in terms of its simplicity and flexibility of fabrication and has the potential for high-density integration.

A large magnetic-field-induced strain (MFIS) of 1150 ppm has been obtained in textured Ni50.5Mn24Ga25.5 polycrystal prepared by vertical zone melting unidirectional solidification. X-ray diffraction measurements of the cubic structure reveal that the preferential orientation along the growth direction is (220). Expansion and shrinkage phenomenon upon the martensitic transition has been observed at 223 K (martensitic transition temperature M-s), indicating the existence of a preferential orientation of martensitic variants to minimize elastic energy. This martensitic transition strain can be enhanced six times, up to 1.5% shrinkage with a bias magnetic field of 1.5 T. (C) 2003 Elsevier B.V. All rights reserved.

Ni80Fe20/Mo magnetic multilayers with a repeat length of 3.4 nm have been fabricated using magnetron sputtering. The interdiffusion coefficient D was determined by measuring the intensity of the X-ray satellite peak arising from the modulation as a function of annealing time. As annealing temperature is below 483 K, the interdiffusion was found to be relatively slow (D < 8.88 x 10(-25) m(2)/s); in that the Ni80Fe20/Mo multilayers have a strong resistance to atomic interdiffusion. The temperature dependence of interdiffusion in the range 343-683 K is described by D = 4.02 x 10(-22) exp(- 0.26 eV/kT) m(2) s(-1). Compared with the extrapolation of published higher temperature data, the interdiffusion at a temperature of 633 K is found to be more rapid, which is suggested to result from moving grain boundaries and coherency strains in the multilayers. (C) 1998 Elsevier Science B.V. All rights reserved.