Ordinary Hall Coefficient Research Articles

Paramagnetic Hall effect in cubic rare earth compounds

The ordinary Hall coefficient R0 has been obtained to get information about conduction state. R0 is positive and almost the same for all the compounds of GdAg1−xIn x. For La to Pr series accompanied by crystallographic transformation, R0 takes a maximum aroundx = 0.2 and decreases to negative with increasing x for x > 0.2.

Hall effect of sputtered NiZr and CoZr metallic glasses near the critical magnetic concentration

With increasing 3d component, the 3d transition-metal Zr amorphous alloys undergo a transition to ferromagnetism at xc=88 at. % Ni, 62 at. % Co, and 38 at. % Fe, respectively. The first two compositions are outside the range of stable melt-spun glasses, but can be prepared by sputtering. In this paper, we present Hall data for sputtered NiZr and CoZr alloys in the vicinity of the critical magnetic composition. For the ferromagnetic glasses, x>xc, the alloys are magnetically soft. Although the NiZr alloys are quite weak magnetically [μ0M(T=0)=0.15 T at 90 at. %], the extraordinary Hall coefficient is very large (Rs=−0.67×10−7 m3/C for the same alloy). In the Co glasses, Rs is positive, but of the same magnitude even though the magnetism is considerably stronger. In the paramagnetic range x<xc, the rapid change in ordinary Hall coefficient close to the critical concentration for ferromagnetism indicates the presence of spin fluctuations, as has been found for the melt-spun FeZr glasses.

Electrical transport properties of UCuAs 2 single crystals

We report resistivity and Hall effect measurements on single crystals of the ferromagnet UCuAs 2. At low temperatures ϱ(T) follows a T 2 law, whereas above 360 K the resistivity indicates Kondo behaviour. The Hall resistivity is positive in the whole temperature range and shows a pronounced maximum below T c: The carrier concentration of 0.18 e -/f.u. derived from the Hall effect and the resistivity data indicates a semimetallic character of UCuAs 2. The temperature variations of the ordinary and spontaneous Hall coefficients are discussed in the framework of existing theories.

Anisotropic magnetoresistance and Hall effects for Ni-Fe-M alloy thin films

The anisotropic magnetoresistivity, Delta rho , and resistivity, rho /sub 0/, were measured and related to the ordinary Hall coefficient, R/sub 0/, and the extraordinary Hall coefficient, R/sub s/, for Ni-Fe and (Ni/sub 89.5/Fe/sub 10.5/)/sub 100-x/ M/sub x/(x >

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The relation between the anisotropic magnetoresistivity ratio Δρ/ρ0 and ordinary Hall coefficient R0 and extraordinary Hall coefficient Rs were studied for Ni-Fe binary alloy and (Ni89.5Fe10.5)M (M =Co, Cu, Nb, Gd, Al, Si and Bi) ternary alloy thin films, to obtain a guiding principle of searching the new materials that show a large value of Δρ/ρ0. The value of Δρ/ρ0 increases with increases in the absolute value of R0 and also shows a maximum (Δρ/ρ0≅4%) at Rs= 0. In the case of the ferromagnetic metals, the large value of Δρ/ρ0 is obtainable under the following conditions, (1) sign of R0 is negative and the absolute value of R0 is large (carrier is electron like and effective carrier density neff is small) and (2) Rs is zero

Composition dependence of electrical and magnetic properties of NiAg this films

NiAg thin films were prepared over the complete composition range by r.f. sputtering. The films are amorphous at room temperature in the composition range from 30 to 50 at.% Ag; they are ferromagnetic for compositions lower than 40 at.% Ag. Electrical resistivity, ordinary and extraordinary Hall coefficients as well as Curie temperature are studied.

Dzyaloshinsky–Moriya interaction in the spin-glass system Cu95−xAuxMn5: Hall effect and ac susceptibility

The effect of gradually changing the background matrix in which Mn ions are imbedded has been investigated in the spin-glass system Cu95−xAuxMn5 by means of low-field Hall effect and ac susceptibility measurements. For the Cu-rich alloys a substantial positive anomalous Hall coefficient is found arising from skew scattering of Dzyaloshinsky–Moriya origin which peaks in each case at the freezing temperature. The concentration x=∼50% appears to be critical in that (a) the anomalous Hall coefficient changes sign, (b) peff undergoes a change of 0.30, and (c) a fairly sudden change of the ordinary Hall coefficient occurs. These results suggest the Mn ions suddenly acquire additional orbital angular momentum at this composition.

An Attempt of Direct Separation of Ordinary and Extraordinary Terms of Hall Effect in a Ferromagnet, Fe3O4

Hall voltage of a ferromagnet, Fe 3 O 4 , was measured on a single crystal platelet as a function of the direction of the external magnetic field. The data was successfully analysed and divided into two terms, those proportional to M x and to B x . Here, M is the magnetization and B is the magnetic flux density and the x axis is perpendicular to the platelet. Thus, ordinary and extraordinary Hall coefficients are separated at each field strength. The result of this separation is much different from that of a conventional method, by linear dependence of the Hall voltage on the external field strength. The difference suggests that higher order terms, those proportional to cubic and higher power of M and B , cannot be ignored in Fe 3 O 4 . Without knowledge of higher order effect, ordinary Hall coefficient cannot be determined since it is small compared with other terms. The validity of discussion on the character of charge carriers must be reexamined, if it is based on the ordinary Hall effect determined co...

Origin of High Upper-Critical-Field in the Superconducting La-Chalcogenides

The “La3X4” (X=S or Se) compound, which undergoes a bcc-to-tetragonal distortion below room temperature, is a strong superconductor. The measurements of the electrical resistivity, the low temperature heat capacity, the ordinary Hall coefficient and the elasticity suggest that the superconducting transition temperature is governed by the density of states at the Fermi surface, whereas the high value of upper-critical-field in the cubic compound originates in an anomalously small mobility in the normal-state electron conduction and it is probably connected with the pre-martensitic transformation

The concentration dependences of the electrical conductivity and ordinary Hall coefficient of nickel ferrous ferrite

Abstract The electrical conductivity and ordinary Hall coefficient of single crystals of nickel ferrous ferrite (NixFe3-xO4) in the composition range 0≤x≤0·9 have been measured at 300 K. The results are compared with theories of hopping in disordered media. Both the conductivity and Hall data permit the radius of the carrier wavefunction to be deduced and it is found that this is about 0·5 A.

Electrical conduction and ordinary Hall effect in thin nickel films

A new interpretation is proposed for the size effects in the electrical resistivity of thin nickel films and in the temperature coefficient of resistivity, starting from theoretical equations, recently published. The size effect in the ordinary Hall coefficient is satisfactorily interpreted in the framework of a polycrystalline model; the agreement is questionable in the framework of a columnar model and the assumption of polycrystalline structure I retained.

Crystallographic transformation and electronic properties in the CsCl-type compounds PrAg1-xInx

The electrical resistivity and Hall resistivity of PrAg1-xInx have been measured. The crystal structure at room temperature is of CsCl type for x or=0.7 it decreases with increasing temperature. The value of Delta rho / Delta T at room temperature has a minimum at x=0.6. The ordinary Hall coefficient R0 is positive at x=0, its magnitude increases with x until x=0.3, where it decreases suddenly as the transformation begins. The relationship between the transformation and the electronic properties is discussed.

Hall effect in amorphous Fe<inf>1-x</inf>B<inf>x</inf>films

Hall resistivity, spontaneous R <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">s</inf> , extraordinary R <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">1</inf> , and ordinary R <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">0</inf> Hall coefficient investigations on Fe-B sputtered films in a wide boron composition and temperature regime are discussed. From the temperature dependence of the initial slope of the Hall curve, Curie T <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">c</inf> and crystallization T <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">k</inf> temperatures were determined. Ordinary Hall coefficients were measured for samples with T <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">k</inf> > T <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">c</inf> from the paramagnetic region. It is concluded that electrical transport in amorphous Fe-B films and amorphous Fe-Si and Fe-Ge films are different.

Electrical resistivity and Hall effect in Fe-Zr amorphous sputtered films

Fe-Zr amorphous films were prepared by a co-sputtering technique, and the electrical resistivity and the Hall effects were investigated. The resistivity ρ at 4.2 K as a function of composition exhibits a broad minimum around 15% Zr, while the magnetization 4πMs indicates a broad maximum at the same composition. The high-field susceptibility dramatically increases below 15% Zr. In the high concentration range the spontaneous Hall coefficient Rs and the magnetization 4πMs decrease, while the resistivity increases, and hence the Hall conductivity γH decreases with increasing Zr content. The ordinary Hall coefficient R0, separated from the spontaneous Hall coefficient Rs, slightly increases with increasing Zr content, showing a positive sign in contrast to that of Co and Ni-base amorphous alloys.

The Hall resistivity of sputtered amorphous Fe-B films

Amorphous Fe-B films were prepared by sputtering in a wide composition range. The magnetization curves at 4.2 K of these amorphous alloys are not saturated easily and the apparent high-field susceptibility drastically increases with a decrease in boron content. The concentration dependence of magnetization exhibits a broad maximum around 14 %B. The Hall resistivity (ρH) as a function of applied magnetic field is also not saturated easily, and this behavior tends to become more significant with decreasing boron content. Such behavior may be correlated with the Invar effects and the stress retained in the amorphous films. The spontaneous Hall coefficient (Rs) calculated from ρH has a marked concentration dependence at low boron content, indicating a decrease in the value. The apparent ordinary Hall coefficient R*o increases dramatically with decreasing boron content, and also the ordinary Hall coefficient Ro is estimated to exhibit a similar tendency. The present results suggest that the electronic structure of amorphous Fe-B alloys is analogous to that of crystalline Fe-Ni Invar alloys.

Hall Effect and Magnetoresistance of Co(SxSe1-x)2, 0 ≤x ≤1

The Hall effect and the transverse magnetoresistance of Co(S x Se 1- x ) 2 for 0 ≤ x ≤1 were observed in the field strength up to 90 kOe in the temperature ranges 4.2 K to 300 K. The ordinary and extraordinary Hall coefficients were determined. The negative ordinary coefficient gave about one electron in the dγ band for 0 ≤ x ≤1. The extraordinary coefficient was positive in the metamagnetic and ferromagnetic states except for a negative coefficient of CoS 2 . The magnetoresistance of the metamagnetic phase changed remarkably by a magnetic saturation. The increase of the resistivity in the magnetized state was about 60 µΩcm as compared with the non-magnetized state.

Magnetic and transport properties of transition-metal based glassy ribbons

In this review, from our systematic studies on transition-metal based amorphous alloys of the type (A <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">x</inf> B <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">1-x</inf> ) <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">75</inf> P <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">16</inf> B <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">6</inf> Al <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</inf> , where A,B, = Fe, Ni, Mn, or Co, we demonstrate that the temperature and the field dependence of the Hall resistivity, ρ <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">H</inf> , yields several useful parameters which characterize the magnetism, and the stability of these systems. The exponent for the fluctuation contribution to the magnetic susceptibility, χ, derived from these studies is found to vary from the value of 1.6, observed in general, to the Heisenberg value of 1.33 for the Fe-rich alloys. The ordinary Hall coefficient for the Ni-rich alloys is found to be negative, while a positive value is observed for all other systems studied so far. The ohmic resistivity, ρ measured simultaneously, is correlated with ρ <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">H</inf> studies in the light of current theories. It is shown that most of the T-dependence of ρ in the metal-metalloid systems is of magnetic origin. Similar studies on the binary amorphous Zr <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">70</inf> (Fe, Co, Ni, Pd, Cu) <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">30</inf> alloys show that these systems can be understood only in terms of the extended Ziman theory. Finally, our recent evidence for deviations from the simple spin-wave theory in the magnetitions of amorphous Fe-Ni alloy system is correlated with ac-susceptibility studies to obtain a probable phase-diagram near the multicrtical point.

Galvanomagnetic Effect of CoS2 Single Crystal

Making use of a single crystal of ferromagnetic CoS 2 , the resistivity, the transverse and longitudinal magnetoresistances and the Hall effect were measured in the temperature range from 4.2 K to 130 K under magnetic field strength up to 15.3 kOe. The ordinary and extraordinary Hall coefficients were determined. By assuming an electron correlation effect on the effective mass and the relaxation time for the majority and minority spin band electrons, the anomalies of resistivity and magnetoresistance were explained. The electron configuration having dγ 1 was confirmed from the ordinary Hall coefficient. The extraordinary Hall coefficient resembles that of Fe. In appendix, determinations of the Curie point and the critical exponents of this crystal were shown.

Electrical and Hall Resistivity in Rare Earth Intermetallic Compounds RAg1-xInx (R: Gd, Tb and Dy)

The electrical resistivity and the Hall resistivity in polycrystalline specimens of RAg 1- x In x have been measured from 4.2 K to room temperature and the paramagnetic region up to room temperature, respectively. The spin disorder resistivity at 0 K, ρ m (0), takes a maximum near the boundary of the different magnetic structures in each compound system, and that above the Curie temperature, ρ m (∞), increases with x in Gd system, while it takes a maximum around x =0.3 in Tb and Dy systems. The ordinary Hall coefficient, R 0 , is positive for all the compounds. On the other hand, the spontaneous Hall coefficient, R s , is negative for all the compounds except GdAg and TbAg and its magnitude increases with x for x ≥0.1 in all the systems. The results have been discussed on the basis of the localized spin model.

The Hall effect, resistivity and magnetic moment of amorphous and polycrystalline iron films

Thin films of iron were prepared by condensation from the vapour phase onto a liquid helium-cooled substrate. The 'as deposited' films possessed large resistivities similar to that of liquid iron and were ferromagnetic. The extraordinary and ordinary Hall coefficients of the films were measured and were found to be of the order of fifty times greater than their crystalline counterparts, although the films possessed a magnetic moment of up to 50% smaller. On annealing these quantities, at a specific temperature, irreversibly changed to values similar to those of the crystalline state. Results are presented for the Hall coefficients of the annealed polycrystalline films from 4.2-500K.