Fuming Yang

Giant magnetic-field-induced strains in Heusler alloy NiMnGa with modified composition

A giant magnetic-field-induced strain (MFIS) of −3100 ppm has been obtained in Heusler alloy Ni52Mn22.2Ga25.8 single crystal in the [001] direction at a temperature from 23 to 31 °C. This MFIS reaches saturation in an applied field about 6 kOe, and exhibits the same amplitude with an opposite sign while the field is perpendicular to the samples. According to a previous model, this MFIS associates with the twin boundary motion. The martensitic self-strain has been found to be 2%, implying a preferential orientation of martensite variants. Results related to the magnetic properties are discussed.

Structure and magnetic properties of TbMn6−xAlxSn6 compounds

In the present work, the influence of the substitution of Al for Mn on the structure and magnetic properties of TbMn6−xAlxSn6 compounds was investigated. With increasing Al concentration the lattice constants a, c, and the unit-cell volume V decrease monotonically. The TbMn6−xAlxSn6 compounds exhibit ferrimagnetic ordering. The magnetic ordering temperature first decreases with increasing Al content up to x=1.5, then increases with further increasing Al content. As for the unsubstituted material, it was found that this series of compounds exhibits a second magnetic transition at lower temperature that is attributed to spin reorientation. The spin-reorientation temperature and the magnetic anisotropy field first decrease with increasing Al content, go through a minimum at x=0.5, then increase with further increasing Al content. The saturation magnetization decreases monotonically with increasing Al content. Two metamagnetic transitions are found in TbMn6Sn6 compounds, one at 0.44 T, and the other at about ...

Enhanced tunability due to interfacial polarization in La0.7Sr0.3MnO3∕BaTiO3 multilayers

BaTiO3 single layer and La0.7Sr0.3MnO3∕BaTiO3 multilayer films were fabricated by laser molecular-beam epitaxy. The voltage tunability of these films was investigated systematically in the frequency ranging from 10kHzto1MHz. The results suggest that the sizable tunability arises from the interfacial polarization which can be strongly suppressed by applied dc biases. In multilayer films, remarkable enhancement in voltage tunability was observed, because the interfacial polarization was greatly enhanced by an interfacial polarization associated possibly with the Maxwell-Wagner relaxation. The authors’ results indicate that the voltage tunability in low frequency (⩽1MHz) has a dominating contribution from the interfacial polarization.

Magnetic properties of a novel Sm3(Fe, Ti)29 phase

Abstract In a systematic study of the Sm 10 Fe 85 Ti x (4.7 x 3 (Fe, Ti) 29 compound has been found to be a new phase, of which the structure is Nd 3 (Fe, Ti) 29 -type. The X-ray diffraction pattern of Sm 3 (Fe 0.933Ti 0.06 7) 29 can be indexed on the monoclinic symmetry with the lattice parameters a = 1.065 nm, b = 0.858 nm, c = 0.972 nm and β = 96.98°. The Sm 3 (Fe 0.933 Ti 0.067 ) 29 compound exhibits ferromagnetic ordering with a Curie temperature T C = 486 K. The saturation magnetization M S is 125 A m 2 /kg at 77 K and 119 A m 2 /kg at room temperature. The room temperature anisotropy field is 3.4 T.

MAGNETIC-PROPERTIES OF A NOVEL SM3(FE, TI)29NY NITRIDE

A new interstitial nitride of Sm3(Fe0.933Ti0.067)29Ny (y=5) has been synthesized. Its x‐ray pattern can be indexed in Nd3(Fe,Ti)29‐type monoclinic symmetry with the lattice parameters of a=1.098 nm, b=0.882 nm, c=0.985 nm, and β=97.50°. The Sm3(Fe0.933Ti0.067)29Ny nitride exhibits ferromagnetic ordering with a Curie temperature Tc=750 K. The saturation magnetization Ms is 160 A m2/kg at 4.2 K and 140 A m2/kg at 293 K. The anisotropy field is 18.1 T at 4.2 K and 12.8 T at 293 K. The coercivity of μ0iHc=0.83 T at 293 K on this new nitride has been developed.

First-order magnetic transition in (Nd, Pr)2Fe14B

Abstract The magnetization of magnetically-aligned (Nd1−xPrx)2Fe14B samples with x = 0.0, 0.2, 0.4, 0.6, 0.8 and 1.0 at 4.2 K has been measured in fields up to 35 T. The first-order magnetization process (FOMP) which has been observed earlier to occur in the magnetization of Nd2Fe14B, measured with the field applied perpendicular to the c axis, becomes more pronounced with increasing praseodymium content, whereas the transition field appears to decrease. A phenomenological analysis is presented in which the misalignment of the grains in the samples has been taken into account. The anisotropy constants up to sixth order obtained in this analysis allow for the calculation of the free energy as a function of the angle between the magnetization vector and the applied fields from which the first-order magnetic transition can be understood.

Structure and magnetic properties of

TbMn6-xTixSn6 compounds with x = 0, 0.5, 1.0, 1.5 and 2.0 have been studied in this paper. All compounds crystallize in the HfFe6Ge6-type structure (space group, P6/mmm). The substitution of Ti for Mn in TbMn6Sn6 results in a linear increase in the lattice constants and the unit-cell volume from a = 5.531 Angstrom, c = 9.025 Angstrom and V = 239.10 Angstrom(3) at x = 0, to a = 5.588 Angstrom, c = 9.150 Angstrom and V = 247.44 Angstrom(3) at x = 2.0. The ordering temperature and the reorientation temperature of the easy axis of these compounds decrease monotonically with Ti content from 423 K and 330 K at x = 0 to 362 K and 285 K at x = 2.0. In thermal magnetic curves a new transition was found at the temperature T-f at which the magnetization begin to increase and T-f increases from 37 K at x = 0 to 150 K at x = 2.0. The saturation magnetization at room temperature decreases linearly with increasing Ti content. The magnetization curves at 1.5 K in fields up to 70 kOe are given and the magnetization values at 1.5 K are derived from them.

Magnetic anisotropy in Pr2(Fe1−xCox)14B compounds

Abstract We have measured the concentration dependence of the Curie temperature, magnetization, anisotropy field and lattice parameters in Pr 2 (Fe 1− x Co x ) 14 B for 0 ⩽ x ⩽ 1. The Curie temperature strongly increases with x . The saturation magnetization at 4.2 K decreases with x after remaining approximately concentration independent up to x = 0.2. The room temperature anisotropy field first decreases with x but after passing through a minimum at about x = 0.7 strongly increases with x . The experimental results are compared with results obtained previously for Nd 2 (Fe 1− x Co x ) 14 B and are discussed in terms of crystal-field effects.

Magnetic properties of R3(Fe,Ti)29Cy carbides (R=Nd, Sm)

R3(Fe, Ti)29Cy carbides (R=Nd, Sm) have been synthesized by gas-solid phase reaction. The Curie temperature is enhanced by carbonation, with values of 651 K and 641 K for Nd and Sm carbides respectively. The saturation magnetization of the carbides is slightly lower than that of their parent alloys. The Sm carbide has a large uniaxial anisotropy field, 21 T at 4.2 K and 14 T at 293 K. A coercivity of mu 0iHc=0.3 T at room temperature in the Sm carbide has been developed.

Magnetic-Properties of CeCuX Compounds

The temperature dependence of the magnetic susceptibility, the magnetization at 4.2 K in fields up to 35 T, and the specific heat between 1.3 and 40 K in fields up to 5 T of the ternary Ce intermetallic compounds CeCuX (X = Si, Ge, Sn) have been studied. All three compounds form in ordered ternary structures related to the hexagonal AlB2 type. Ferromagnetic order is found below 14.9 K for CeCuSi and below 10.2 K for CeCuGe. The magnetic order of CeCuSn below 8.6 K is of antiferromagnetic type but probably complex, as indicated by a double peak in the specific heat and the occurrence of a very low zero‐field moment.