Electrical resistivity and magnetic phase transitions in modified FeRh compounds

Баранов, Н. В.; Barabanova, E. A.

doi:10.1016/0925-8388(94)01375-6

Cited by 98 publications

(95 citation statements)

References 24 publications

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“…The transition temperature is suppressed under the application of external magnetic field because of the reduction of the free energy of the FM phase [19]. This transition temperature suppression by an external field enables the derivation of some thermodynamic parameters from magnetization measurements [20], [21], which gives consistent results with thermal measurements [2], [7].…”

Section: Introductionsupporting

confidence: 63%

Magnetothermodynamic Properties and Anomalous Magnetic Phase Transition in FeRh Nanowires

et al. 2018

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Thermal properties of submicron wires of Pd-doped FeRh alloys are evaluated from measurements of transport properties around the first order antiferromagnetic to ferromagnetic phase transition. Recently, in a submicron wire of FeRh alloy, an asymmetric structure between heating and cooling processes was reported in the vicinity of the phase transition temperature. A system where finitesize effects appear is expected to show different magnetic and thermal properties from those in bulk and thin film. However, thermal or magnetization measurements are difficult to perform on samples with such a tiny volume. Here, we demonstrate a quantitative evaluation of thermal properties in thin films and submicron wires of B2-ordered Pd-doped FeRh alloy grown on MgO (001). Resistivity measurements on a series of wires with different width reveal that the anomaly in the resistance change is enhanced in narrow wires. As the transport properties in submicron wires sensitively reflect those magnetic states, the entropy change and irreversible energy loss during the first order phase transition have been determined via resistance measurements. We find a larger energy loss in smaller samples where wider hysteresis loops appear in temperature-driven measurements. This method can be a probe to evaluate the finitesize effect induced by a restricted magnetic domain nucleation process during the phase transition.Index Terms-FeRh alloys, first order phase transition, metamagnetic transition, thin films, submicron wires.

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Section: Introductionsupporting

confidence: 63%

Magnetothermodynamic Properties and Anomalous Magnetic Phase Transition in FeRh Nanowires

et al. 2018

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“…The crux of these features of this CsCl-structured material is the first order transition from an antiferromagnetic (AFM) to ferromagnetic (FM) state when the temperature is increased above T m = 320 K [1,2]. In this context the drop of the electrical resistivity that is observed across the metamagnetic transition is of central interest.…”

Section: Pacs Numbers: Valid Pacs Appear Herementioning

confidence: 99%

“…In this context the drop of the electrical resistivity that is observed across the metamagnetic transition is of central interest. Furthermore, if the AFM to FM transition is induced by an applied magnetic field, a pronounced magnetoresistance (MR) effect is found experimentally with a measured MR ratio ∼ 50% at room temperature [2][3][4]. The temperature of the metamagnetic transition as well as the MR ratio can be tuned by addition of small amounts of impurities [2,[5][6][7][8].…”

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confidence: 95%

Temperature-dependent transport properties of FeRh

et al. 2017

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The finite-temperature transport properties of FeRh compounds are investigated by first-principles Density Functional Theory-based calculations. The focus is on the behavior of the longitudinal resistivity with rising temperature, which exhibits an abrupt decrease at the metamagnetic transition point, T = Tm between ferro-and antiferromagnetic phases. A detailed electronic structure investigation for T ≥ 0 K explains this feature and demonstrates the important role of (i) the difference of the electronic structure at the Fermi level between the two magnetically ordered states and (ii) the different degree of thermally induced magnetic disorder in the vicinity of Tm, giving different contributions to the resistivity. To support these conclusions, we also describe the temperature dependence of the spin-orbit induced anomalous Hall resistivity and Gilbert damping parameter. For the various response quantities considered the impact of thermal lattice vibrations and spin fluctuations on their temperature dependence is investigated in detail. Comparison with corresponding experimental data finds in general a very good agreement. PACS numbers: Valid PACS appear hereFor a long time the ordered equiatomic FeRh alloy has attracted much attention owing to its intriguing temperature dependent magnetic and magnetotransport properties. The crux of these features of this CsCl-structured material is the first order transition from an antiferromagnetic (AFM) to ferromagnetic (FM) state when the temperature is increased above T m = 320 K [1,2]. In this context the drop of the electrical resistivity that is observed across the metamagnetic transition is of central interest. Furthermore, if the AFM to FM transition is induced by an applied magnetic field, a pronounced magnetoresistance (MR) effect is found experimentally with a measured MR ratio ∼ 50% at room temperature [2][3][4]. The temperature of the metamagnetic transition as well as the MR ratio can be tuned by addition of small amounts of impurities [2,[5][6][7][8]. These properties make FeRh-based materials very attractive for future applications in data storage devices. The origin of the large MR effect in FeRh, however, is still under debate. Suzuki et al. [9] suggest that, for deposited thin FeRh films, the main mechanism stems from the spin-dependent scattering of conducting electrons on localized magnetic moments associated with partially occupied electronic dstates [10] at grain boundaries. Kobayashi et al. [11] have also discussed the MR effect in the bulk ordered FeRh system attributing its origin to the modification of the Fermi surface across the metamagnetic transition. So far only one theoretical investigation of the MR effect in FeRh has been carried out on an ab-initio level [12].The present study is based on spin-polarized, electronic structure calculations using the fully relativistic multiple scattering KKR (Korringa-Kohn-Rostoker) Green function method [13][14][15]. This approach allowed to calculate the transport properties of FeRh at finite temperature...

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“…Fe and Rh will form alloys at any composition, however a B2-ordered compound is the equilibrium state for stoichiometries in the near-equiatomic range 49-53% atomic Fe 17,18 , a large entropy release 19 , a large drop in the resistivity 14 , and a large increase in the carrier concentration 20 . Neutron diffraction 21,16 and more recently XMCD measurements 22 , and is suppressed by ~8 K/T of applied magnetic field 25,15 . This rich array of physical behavior depends critically on achieving the proper B2-ordered structure and so permits a wide variety of measurement techniques to be deployed to detect proper chemical ordering in a specimen, making it a convenient example to demonstrate a method of growing high-quality ordered alloy epilayers.…”

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Sputter Growth and Characterization of Metamagnetic B2-ordered FeRh Epilayers

Graët

Vries

McLaren

et al. 2013

JoVE

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Chemically ordered alloys are useful in a variety of magnetic nanotechnologies. They are most conveniently prepared at an industrial scale using sputtering techniques. Here we describe a method for preparing epitaxial thin films of B2-ordered FeRh by sputter deposition onto single crystal MgO substrates. Deposition at a slow rate onto a heated substrate allows time for the adatoms to both settle into a lattice with a well-defined epitaxial relationship with the substrate and also to find their proper places in the Fe and Rh sublattices of the B2 structure. The structure is conveniently characterized with X-ray reflectometry and diffraction and can be visualised directly using transmission electron micrograph crosssections. B2-ordered FeRh exhibits an unusual metamagnetic phase transition: the ground state is antiferromagnetic but the alloy transforms into a ferromagnet on heating with a typical transition temperature of about 380 K. This is accompanied by a 1% volume expansion of the unit cell: isotropic in bulk, but laterally clamped in an epilayer. The presence of the antiferromagnetic ground state and the associated first order phase transition is very sensitive to the correct equiatomic stoichiometry and proper B2 ordering, and so is a convenient means to demonstrate the quality of the layers that can be deposited with this approach. We also give some examples of the various techniques by which the change in phase can be detected.

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Electrical resistivity and magnetic phase transitions in modified FeRh compounds

Cited by 98 publications

References 24 publications

Magnetothermodynamic Properties and Anomalous Magnetic Phase Transition in FeRh Nanowires

Magnetothermodynamic Properties and Anomalous Magnetic Phase Transition in FeRh Nanowires

Temperature-dependent transport properties of FeRh

Sputter Growth and Characterization of Metamagnetic B2-ordered FeRh Epilayers

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