Tb Magnetic Moments Research Articles

Magnetic behaviour of Tb impurities in Gd andY single crystals: a nuclear orientation study

The low temperature nuclear orientation of160Tb impurities in Gd andY single crystals has been studied in the temperature range 7–40 mK andin the external magnetic field range 0–7.3 T applied alonga-, b- andc-crystal axes. In the case of Tb in Gd we found a considerable noncollinearity of the Tb magnetic moment with respect to the magnetic external field direction even for highBext. In the case of Tb in Y the results cannot be described by a simple model, taking into account the simultaneous influence of the crystal andexternal magnetic fields. Some new proposals for interpretation of the experimental dat are given.

Magnetic ordering in TbNiGe 2 and HoNi 0.64Ge 2 by neutron diffraction

Neutron diffraction measurements performed on polycrystalline samples of TbNiGe 2 and HoNi 0.64Ge 2 show that both exhibit at 4.2 K uniaxial antiferromagnetic ordering with G-mode. The magnetic moments of Tb and Ho are oriented parallel to the c-axis of a CeNiSi 2 type structure and at 4.2 K are 8.8μ B and 6.4μ B respectively.

Nuclear orientation study of160Tb impurity in gadolinium single crystal

The low temperature nuclear orientation of160Tb in gadolinium single crystal has been studied in the temperature range 5–60 mK and in the external magnetic field Bext ≤9 T, applied both in the a- and c-axis directions. The obtained results indicate the noncollinearity between the Tb magnetic moments and the magnetization of the gadolinium matrix.

159Tb NMR in TbNi3and Related Compounds

159 Tb spin echo NMR measurements have been done on TbNi 3 , Tb 1- x Y x Ni 3 for x ≤0.4, Tb(Ni 1- x Cu x ) 3 for x ≤0.1 and Tb(Ni 0.96 Al 0.04 ) 3 . The NMR spectrum becomes rather broad with substituting Ni by Cu, while that for Tb(Ni 0.96 Al 0.04 ) 3 shows a well-resolved satellite structure. The magnetic moment of Tb in TbNi 3 is deduced to be 8.1 µ B for site I and 7.8 µ B for site II from an analysis of the electric quadrupole interaction of 159 Tb on the basis of a molecular field Hamiltonian.

Pressure dependence of the terbium magnetic moment

In a previous work on lSlTa in terbium [1] we questioned the pressure dependence of the Tb magnetic moment as determined by bulk magnetisation measurements with high applied field [2,3]. However, since impurity atoms in ferromagnetic hosts sometimes show an impurity associated own temperature and pressure dependence, data for different probe atoms are required in order to find out the host associated properties. We have therefore measured the pressure dependence of the 1HCd local field at different temperatures in zero applied field. The relative pressure dependence of the fields are summarized below.

NMR study of crystal field effect on Tb in TbNi 2

Spin echo NMR measurements on 159Tb have been done at 1.6 K in the magnetically ordered state of the cubic Laves phase TbNi 2 compound. The magnetic hyperfine interaction and the electric quadrupole interaction parameters have been observed to be 2924±3 MHz and 258.3±3 MHz, respectively. The magnetic moment of Tb is deduced to be 7.55 μ B from the electric quadrupole splitting of 159Tb on the basis of a molecular field Hamiltonian.

Anomalous magnetoresistance effect in sputtered TbFeCo relating to dispersed magnetic moment

The electric resistance of sputtered TbFeCo has been measured at room temperature as a function of magnetic field perpendicular to the film plane. Two kinds of anomalous magnetoresistance have been observed. One is a magnetoresistance peak in the magnetization-reversal region. The other is a reversible change proportional to the applied magnetic field, appearing in the other region. The magnetoresistance peak agrees well with a curve calculated from an experimental Hall loop. The magnetoresistance peak is found to originate from magnetic domain walls. The linear magnetoresistance change for transition-metal-dominant samples appears in a direction opposite to that for rare-earth-dominant samples. It is explained in terms of the reversible orientation change in the non-S-state Tb magnetic moment, which is dispersed because of random magnetic anisotropy. >

Magnetism of the Tb 2Fe 14−xCo xB system

The Tb 2Fe 14− x Co x B materials were synthesized for the entire composition range ( x = 0–14) and studied by X-ray and magnetometry methods. All materials have a tetragonal crystal structure with decreasing lattice parameters upon Co substitution. The Curie temperature markedly rises for alloys with low Co content. Saturation magnetization at 77 K reaches a slight maximum around x ≈ 1 and gradually decreases for higher Co concentrations. An antiparallel coupling of 3d and Tb magnetic moments is inferred from saturation magnetization data. Anisotropy fields exhibit a maximum at low Co contents, but they decrease rapidly for x > 5. A spin reorientation (axis-to-plane) occurs at high temperature in materials with x ⩾ 12.5 due to competing effects of the terbium sublattice anisotropy and the 3d sublattice anisotropy. The spin-reorientation temperature becomes lower for alloys with higher Co content. The observed magnetic behavior is discussed in terms of preferential Co substitution into 16 k 2 sites and changes in the 3d sublattice due to Co introduction. A magnetic phase diagram is constructed for the Tb 2Fe 14- x Co x B system and compared with that of Pr 2Fe 14- x Co x B and Nd 2Fe 14 - x Co x B systems.

Influence of Ni-concentration on the magnetic structure in Tb(Cu, Ni)2 system

A powder sample of orthorhombic Tb(Cu0.7Ni0.3)2 has been studied by neutron diffraction at T = 4.2 K and above the Curie temperature. It is found that this compound is ferromagnetically ordered at 4.2 K. The magnetic moment of Tb in this compound is (9.2 ± 0.2)μB, with components (2.2 ± 0.2, 0, 8.9 ± 0.1)μB. The influence of the Ni-concentration on the magnetic structure is discussed in the whole Tb(Cu, Ni)2 system.

Elastic neutron diffraction study of TbAl 2 and HoAl 2

Powder samples of TbAl 2 and HoAl 2 have been studied by neutron diffraction for temperatures down to 4.2°K. It is found that both compounds are ferromagnetically ordered at 4.2°K. The form factor has been measured between sin θ⧸ λ = 0.11 and 0.55 Å −1. Within the experimental error we find agreement of the measured form factor with the free ion form factor. The magnetic moment of Tb in TbAl 2 is 9.2 ± 0.2micro B and that of Ho in HoAl 2 is 8.1 ± 0.2micro B .