AC susceptibility in Y1−xTbxCo2 compounds (original) (raw)
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Magnetization and AC susceptibility of TbxY1-xCo2 compounds
Journal of Magnetism and Magnetic Materials, 1983
Magnetization and ac susceptibility measurements have been performed on Tb,Y, _,Co, compounds. Samples with x > 0.1 order ferromagnetically below room temperature. The cobalt magnetic moments in these compounds are induced by the internal magnetic field exerted by the terbium moments on the cobalt atoms. The ac susceptibility measurements indicate a change from second order to first order in the ferromagnetic transition for samples with x-values equal or smaller than 0.5.
Structural, magnetic, and magnetothermal properties of the Tb0.3Dy0.7Co2 compound
Physics of the Solid State, 2011
A complex investigation of the structural, magnetic, and magnetothermal properties of the Tb 0.3 Dy 0.7 Co 2 compound synthesized with the use of high purity rare earth metals has been performed. The phase composition has been controlled using the X ray structural analysis, and the topology of the alloy sur face has been investigated using atomic force microscopy. It has been established that the Tb 0.3 Dy 0.7 Co 2 compound is single phase, while the samples selected for measurements possess a clearly pronounced tex ture. The magnetization has been measured using a vibrating sample magnetometer in the fields up to 100 kOe in a temperature range from 4.2 to 200 K. The Curie temperature of the compound is 170 K. The data on the temperature dependence of heat capacity of Tb 0.3 Dy 0.7 Co 2 have been obtained. The magnetocaloric effect ΔT has been measured by a direct method in the fields up to 18 kOe applied both along and perpendic ularly to the texture axis. The anisotropic behavior of the magnitude ΔT for this compound, which possesses the cubic structure, has been found. The maximum value of the magnetocaloric effect ΔT = 2.3 K (ΔH = 18 kOe) has been observed upon applying the magnetic field along the texture axis.
Field effect on itinerant electron magnetism of Y1$minus;xErxCo2 compounds
Physica B: Condensed Matter, 2003
Thermopower S and electrical resistivity r of cubic Laves phase pseudo-binary compounds Y 1Àx Er x Co 2 were measured from 2 to 300 K in magnetic fields up to 15 T: S and r show a strong field dependence in a vicinity of the magnetic ordering temperature. The reduction of the exchange magnetic field B exc acting on Co 3d electrons by Y substitution for Er results in a separation of magnetic transition temperatures of Er and Co subsystems in Y 0:4 Er 0:6 Co 2 : The collapse of the itinerant Co 3d moments of Y 0:4 Er 0:6 Co 2 is induced by applying external magnetic field about 10 T:
On the magnetic properties of the Y1−xGdxCo4B compounds
Solid State Communications, 1992
Magnetic phase transitions in Yl.xGdxCO4 B with x ranging from 0 to 1 have been determined in the temperature range of 77 to 600K. The compensation temperature is found in the compounds with x ~ 0.6,while in the rest compounds a spin reorientation from the c-axis towards the basal plane upon decreasing temperature is observed. On the basis of the observed Curie and compensation temperatures the intersublattice exchange interaction coefficient has been derived and the contribution of the anisotropic exchange interaction to the anisotropy energy of the Gd containing compounds has been estimated.
Journal of Alloys and Compounds, 1998
Electrical resistivity, magnetization and AC susceptibility measurements have been carried out to investigate the order of the magnetic phase transition in (Er Tb)Co compounds. In this system a changeover from first-to second-order transition at about x 50.60 was 12x x 2 c observed. This result is discussed in the framework of the generalized Inoue-Shimizu phenomenological model. Moreover, a microscope explanation about the order of the phase transition in terms of spin fluctuation and metamagnetism of the Co-3d subsystem is offered.
Spontaneous and field-induced magnetic transitions in YBaCo2O5.5
Journal of Magnetism and Magnetic Materials, 2009
A detailed study of magnetic properties of cobaltite YBaCo 2 O 5.5 has been performed in high (up to 35 T) magnetic fields and under hydrostatic pressure up to 0.8 GPa. The temperatures of paramagnet-ferromagnet (PM-FM) and ferromagnet-antiferromagnet (FM-AF) phase transitions and their pressure derivatives have been determined. It has been revealed that in the compound with yttrium, in contrast to those with magnetic rare earth atoms, the AF-FM field-induced magnetic phase transition is accompanied by a considerable field hysteresis below 240 K, and the magnetic field of 35 T is not sufficient to complete this transition at low temperatures. The hysteresis value depends on the magnetic field sweep rate, which considered as an evidence of magnetic viscosity that is especially strong in the region of coexistence of the FM and AF phases. High values of susceptibility for the field-induced FM phase show that Co spin state in these compounds changes in strong magnetic field.
Magnetism on the Surface of the Bulk Paramagnetic Intermetallic Compound YCo2
Physical Review Letters, 2005
Using full-potential electronic structure calculations, we predict that the (111) surface of the cubic Laves phase Pauli paramagnet YCo 2 is ferromagnetic. The magnetism of the (111) surface is independent of the termination of the surface, does not extend beyond two Co layers, and is related to the field-induced metamagnetism of the bulk. YCo 2 appears to be a prominent candidate to demonstrate the phenomenon of surface-induced itinerant magnetism localized in two dimensions.
Electronic structure and magnetic properties of the Th Y1−Co4B solid solution
Computational Materials Science, 2010
Detailed theoretical and experimental investigations of the electronic and magnetic properties of the Th x Y 1Àx Co 4 B compounds have been performed. The neutron powder diffraction shows that by Th for Y substitution, Th atoms occupy preferentially one (1a) of the two Y sites (1a and 1b). The preferential occupation on 1a and 1b crystal sites investigated by theoretical calculations is in good agreement with powder neutron diffraction results. The magnetic properties of the Th x Y 1Àx Co 4 B compounds are strongly influenced by the Th content x. The Curie temperature of the compound decreases with Th content from 380 K for YCo 4 B to 303 K for ThCo 4 B. The Th for Y substitution alter the magnetic coupling of the Co 2c atoms, which have the dominant contribution to the magnetization of the system. The magnetic moments behavior in the Th x Y 1Àx Co 4 B compounds is also related to the preferential occupation of crystallographic 1a and 1b sites by Th and Y atoms, respectively. The agreement between the calculated magnetic moments and the corresponding experimental results is discussed. All theoretical investigations of the electronic and magnetic properties of the system have been done using the Korringa-Kohn-Rostoker (KKR) band structure method in the ferromagnetic state. The substitutional disorder in the system has been accounted for by means of Coherent Potential Approximation (CPA).
Observation of ferromagnetic surface of paramagnetic YCo 2
Journal of Physics: Conference Series, 2008
Here we present results on the experimental observation of intrinsic surface magnetism of the bulk paramagnetic material YCo 2. As predicted by theory, the observed magnetism of the low-index crystallographic (111) plane of YCo 2 is explained by the increasing of density of electronic states at the Fermi level due to the reduced atomic coordination at the surface. Since this magnetic order exists at room temperature, YCo 2 shows great potential for an application in magnetic nanotechnology.
Ab initio studies of structure and magnetic structure in YCo3H2
Journal of Alloys and Compounds, 2005
We present an ab initio density functional study of magnetic phase transitions in the YCo 3 H 2 system. The augmented plane wave and local orbital method as employed in the WIEN2K code is used to predict the structure and electronic structure of this compound. Comparison is made with recent X-ray diffraction and magnetization studies. The calculations suggest that the YCo 3 H 2 system is ferrimagnetic in character. Further, fixed spin moment calculations are used to predict and interpret magnetic phase transitions observed in externally applied magnetic fields.