The experimental methods that have been used to evaluate the youngs modulus cover a wide range of techniques such as nanoindentation ni and resonant ultrasound spectroscopy rus 5, 6. Heusler hh compounds, selected from more than 100 hhs, is carried out in this paper. F casper 1, t graf 1,2, s chadov 1, b balke 1 and c felser 1,3. The nomenclature in literature varies a lot, ranging from sorting the elements alphabetically. Structural, electronic, magnetic, and optical properties. Apr, 2015 heusler compounds are a remarkable class of materials with more than members and a wide range of extraordinary multifunctionalities including halfmetallic hightemperature ferri and ferromagnets, multiferroics, shape memory alloys, and tunable topological insulators with a high potential for spintronics, energy technologies, and magneto. Apr, 2015 the magnetic structure of the mn 2 heusler compounds is distinguished from the co 2 heusler compounds, although both families follow the slater pauling curve, independent of the structure type, and continuous across the compensation point 34 34. Design scheme of new tetragonal heusler compounds for spin. Published 27 april 2012 2012 iop publishing ltd semiconductor science and technology, volume 27, number 6. Although the half heusler alloys like nimnsb have attracted a lot of interest, the second family of heusler compounds, the socalled full heusler alloys have been studied much more extensively due to the existence of diverse magnetic phenomena,11,12 mainly the transition from a ferromagnetic phase to an antiferromagnetic one. Heusler compounds with perpendicular magnetic anisotropy.
Especially heusler compounds as halfmetallic ferromagnetic and topological insulators are important in. An approach to design compensated ferrimagnetic heusler alloys is established. The free carrier spin polarization at the fermi level is an important property and is given by. The search for stable halfmetallic ferromagnets and ferromagnetic semiconductors with curie. Are aupdtm t sc, y and m al, ga, in, heusler compounds. New materials must be found for satisfying the different types of requirement. Heusler compounds are magnetic intermetallics with facecentered cubic crystal structure and a composition of xyz halfheuslers or x 2 yz fullheuslers, where x and y are transition metals and z is in the pblock. Crystal structure of new heusler compounds request pdf. Crystal structure of heusler compounds springerlink. We investigated the thermoelectric properties of the ternary half heusler compound, tinisn, when introducing c and n.
We present evidence for magneticfieldinduced weyl physics in these compounds, namely, a chiral anomaly negative magnetoresistance and an anomalous hall effect ahe with a large anomalous hall angle. While they have been known for a long time, 1 it is only in recent years that a wide range of their extraordinary functionalities, including halfmetallic hightemperature ferri and ferromagnets, 2 multiferroic shape memory alloys, 35 and topological insulators, 68 have. Novel halfmetallic and spingapless heusler compounds by. In the heusler clan, pd 2mnz z in, sn and sb type compounds have gained lot of attention due to their diverse magnetic structures 2025. Design scheme of new tetragonal heusler compounds for spintransfer torque applications and its experimental realization heusler compounds represent a remarkable class of materials with more than 1500 members. Firstprinciples study of electromechanical and polar properties in perovskite oxides and halfheusler semiconductors by anindya roy dissertation director. Structural, electronic, magnetic, and optical properties of. Fecher, and claudia felser abstract spintronics is a multidisciplinary.
Simple rules for the understanding of heusler compounds. Chapter 2 new heusler compounds and their properties benjamin balke, gerhard h. Magnetic materials underpin modern technologies, ranging from data storage to energy conversion to contactless sensing. This presents the possibility of realizing noncentrosymmetric superconductors in the family of heusler compounds. Spin polarised heusler compounds computer file, 2006. This database provides information on three families of heusler alloys, full heuslers a 2 bc, half heuslers abc and inverse heuslers abac. Heusler alloys consist of approximately two parts of copper, one of manganese, and one of tin. Highthroughput machinelearningdriven synthesis of full. May 23, 2019 in this paper, we report a new type of mnrich heusler compound with a cubic unit cell, a 0. The mnsb terminated surfaces of the halfheusler compounds present properties similar to the bulk compounds and, although the halfmetallicity is lost, an important spinpolarisation at the fermi level.
In the present work we suggest a recipe for finding tetragonal heusler compounds with perpendicular magnetic anisotropy pma that also exhibit large tunneling magnetoresistance tmr when used as electrodes in magnetic tunnel junction devices with suitable tunneling barrier materials. The extensive tunability of the heusler compounds through chemical substitutions and structural motifs makes the family especially interesting. Jun 22, 2017 halfheusler alloys rumnz z p, as are studied in the framework of density functional theory dft. Heusler compounds as thermoelectric materials based on the calculated electrical transport properties, advanced functional materials on deepdyve, the largest online rental service for scholarly research with thousands of academic publications available at your fingertips. Theory of heusler and fullheusler compounds request pdf. Tetragonal superstructure of the antiskyrmion hosting heusler compound mn1. Potential motivation of such research activities are fueled by the discovery of diverse physical and functional properties having important technological applications.
Heusler alloy, any of the first magnetic alloys composed of metals that, in their pure state, are not magnetic. Basics and prospective of magnetic heusler compounds. We performed densityfunctional theory calculations for 286 heusler compounds. In this article we highlight recent major developments in the field of.
In this article we highlight recent major developments in the. Heusler alloys have been a significant topic of research due to their unique electronic structure, which exhibits halfmetallicity, and a wide variety of properties such as magnetocalorics, thermoelectrics, and magnetic shape memory effects. Pdf a first principles study of co2mnsi a fullheusler. Heusler compounds are a remarkable class of materials with more than members and a wide range of extraordinary multifunctionalities including halfmetallic hightemperature ferri and ferromagnets, multiferroics, shape memory alloys, and tunable topological insulators with a high potential for spintronics, energy technologies, and magnetocaloric. Basics and prospectives of magnetic heusler compounds. It was suggested to have heusler structure and show weak ferromagnetism at room temperature. Sep 11, 2018 gdptbi and ndptbi belong to the heusler family of compounds and are conventional antiferromagnets below 9 and 2.
For spintronic application, the magnetic heusler compounds and halfmetals, in particular, are of utmost interest. A machinelearning model has been trained to discover heusler compounds, which are intermetallics exhibiting diverse physical properties attractive for applications in thermoelectric and spintronic materials. Halfheusler alloys rumnz z p, as are studied in the framework of density functional theory dft. The centrosymmetry is always lost in quaternary heusler compounds with 1. New heusler compounds and their properties benjamin balke, gerhard h. We present evidence for magneticfieldinduced weyl physics in these compounds, namely, a chiral anomaly negative magnetoresistance and an anomalous hall effect ahe with a large anomalous hall angle over a wide range of temperature. Normally, the compounds crystallize in cubic structures except when the y orand z. Heusler compounds offer advantages for cppgmr and mram high spin polarization good for cppgmr. This presents the possibility of realizing noncentrosymmetric superconductors in the family of heusler. When one of the two x atoms is replaced by a different transition metal m, a new quaternary heusler alloy with the formula xmyz is obtained.
Slaterpauling behavior and origin ofthe halfmetallicity ofthe fullheusler alloys. These properties depend on the number of valence electrons per formula unit allowing tuning of properties through composition and alloying. The most reported elastic property for heusler alloys is youngs modulus. Heusler alloys properties, growth, applications claudia. Both of them are expected to affect the ultrafast magnetization dynamics occurring on the femtosecond time scale. The addition of c or n to tinisn leads to an enhanced power factor and a decreasing lattice thermal conductivity by point defect phonon scattering.
Accelerated discovery of new magnets in the heusler alloy. Chapter 2 new heusler compounds and their properties. Crystal structure, composition and heat treatment were found to be important parameters for determining magnetic properties. Improving these properties requires knowledge of crystal structures, which occur in three subtle variations heusler, inverse heusler, and cscltype structures that are difficult, and at. Our results show that the z 2 topological order is due to a single band inversion at the. Sellmyer this thesis is devoted to experimental studies of heusler compounds cofecral. Halfheusler phases and nanocomposites as emerging highzt thermoelectric materials volume 26 issue 22 s. All the calculations are done using the full potential linearized augmented plane wave fplapw method. Novel halfmetallic and spingapless heusler compounds. Tetragonal superstructure of the antiskyrmion hosting.
Kulwinder kaur and jaswinder kaur, exploration of thermoelectricity in scrhte and zrptpb half heusler compounds. Especially heusler compounds as halfmetallic ferromagnetic and topological insulators are important in condensed matter science due to their potential in magnetism and as materials for energy conversion. In this chapter, a detailed description of the crystal structure as well as different types of atomic disorder are given. Surface properties of the half and fullheusler alloys. Professor david vanderbilt this thesis discusses electromechanical and polar properties in two wellknown classes of materials, perovskite oxides and halfheusler compounds, using. Firstprinciples study of new quaternary heusler compounds. Heusler compounds are promising materials in many fields of contemporary research. In contrast to this the ni terminated surface shows an almost zero net spinpolarisation. Intermetallic heusler alloys are amongst the most attractive halfmetallic systems due to the high curie temperatures and the structural similarity to the. Design of compensated ferrimagnetic heusler alloys for. In native states, these halfheusler compounds are identified as being topologically nontrivial. Pd 2mnsb was probably the first compound of this kind reported in 1960 by hames 20. A small lack of compensation produces giant exchange bias and large coercivity. Extensive experimental studies showed that the majority of heusler compounds order ferromagnetically in stoichiometric composition.
When strictly following this new rule, some candidates in the class of heusler compounds are expected to be completely compensatedferrimagnetic but with a spin polarization of 100% at the fermi. Heusler compounds are a promising class of materials. Many of these compounds exhibit properties relevant to spintronics, such as magnetoresistance, variations of the hall effect. The alloys are named after fritz heusler, 19thcentury german mining engineer and chemist. Heusler alloys are continuing to be at the forefront of active research 15. Heusler compounds are a large group of intermetallic compounds with over members with similar crystal structures having a vast array of tunable properties. Cpp gmr, mram and making them by sputtering matthew carey spin transfer technologies. Topological electronic structure in halfheusler topological. While they have been known for a long time, 1 it is only in recent years that a wide range.
For halfmetallic heusler compounds the total spin magnetic moment mt scales linearly with the number of the valence electrons zt in the unit cell. Novel halfmetallic and spingapless heusler compounds yunlong jin, ph. Review of heusler compounds zhaoqiang bai,1, 2 lei shen,1, guchang han,2 and yuan ping feng1, 1 department of physics, national university of singapore, 2 science drive 3, singapore 117542, singapore 2 data storage institute, agency for science, technology and research, 5 engineering drive 1, singapore 117608, singapore abstract. A first principles study of co2mnsi a fullheusler compound. An overview of the possible applications of heusler compounds in stt devices is given in sections 5, with subsections 5. Gdptbi and ndptbi belong to the heusler family of compounds and are conventional antiferromagnets below 9 and 2. This book gives an overview of the physics of heusler compounds ranging from fundamental properties of these alloys to their applications. In general, heusler compounds crystallize in the cu 2 mnaltype structure but in many cases certain types of disorder are observed.
Anomalous hall effect in weyl semimetal halfheusler. Improving these properties requires knowledge of crystal structures, which occur in three subtle variations heusler, inverse heusler, and cscltype structures that. In this paper, we report the synthesis, crystal structure, and disorder type of the new heusler compounds mn2ruge, mn2rhga, and the redetermination of the crystal structure of mn2rusn. Engineering of magnetic materials for developing better spintronic applications relies on the control of two key parameters. The mnsb terminated surfaces of the half heusler compounds present properties similar to the bulk compounds and, although the halfmetallicity is lost, an important spinpolarisation at the fermi level. Heusler materials, initially discovered by fritz heusler more than a century ago, have grown into a family of more than compounds, synthesized from combinations of more than 40 elements. These heusler alloys present an interesting class of. In general, half heusler materials xyz can be understood as compounds consisting of a covalent and an ionic part.
Halfheusler phases and nanocomposites as emerging highzt. Compounds with eight valence electrons per formula unit are closely related to classical semiconductors, such as silicon and gaas. A first principle study, journal of alloys and compounds, 10. In general, halfheusler materials xyz can be understood as compounds consisting of a covalent and an ionic part. Fullheusler compounds crystallize in the l2 1 structure. For each of these families, we provide calculations for numerous systems. However, the design of unconventional semiconductors based on 18 for half heusler compounds or 24 valence electrons for heusler compounds is also possible, resulting in band gap widths of more than 1 ev. Tetragonal superstructure of the antiskyrmion hosting heusler. Heusler compounds represent a remarkable class of materials with more than 1500 members. Full heusler alloys represent a class of ternary intermetallic compounds with the general formula x 2 yz, where x and y are transition metals and z is a main group element. We show that many of these compounds show a halfmetallic behavior, however in contrast to the halfheusler alloys the energy gap in the minority band is extremely small due to states localized only at the co fe, rh or ru sites which are not present in the. Tunability, especially of m s, in order to optimize the con.
However, the development of a new highperformance magnet is a long and often unpredictable process, and only about two dozen magnets are featured in mainstream applications. Design of compensated ferrimagnetic heusler alloys for giant. The x and y atoms have a distinct cationic character, whereas z can be seen as the anionic counterpart. We describe a systematic pathway to the design of novel magnetic materials, which demonstrates a high. Effect of c and n addition on thermoelectric properties of. We investigated the thermoelectric properties of the ternary halfheusler compound, tinisn, when introducing c and n. The progress of recent study and future prospect of halfmetallic heusler compounds will be presented. Ferromagnetic thin films of heusler compounds are highly relevant for spintronic applications owing to their predicted halfmetallicity, that is, 100% spin polarization at the fermi energy.
Insitu anneal with heusler top surface free nothing to stress heusler 2 hypothesis. The nomenclature in literature varies a lot, ranging from sorting the elements alphabetically, according to their electronegativity or randomly, and thus, all three possible permutations can be found. Heusler compounds as thermoelectric materials based on the calculated electrical transport properties. In contrast to this the ni terminated surface shows an. We describe a systematic pathway to the design of novel. Heusler compounds with perpendicular magnetic anisotropy and. Manganeserich heusler compounds are attracting much interest in the context of spin transfer torque and rareearth free hard magnets. These heusler alloys present an interesting class of ferromagnetic materials for spintronic applications since they are predicted to be spin gapless semiconductors and have halfmetallic properties with 100 % spin polarization at the fermi level.
In this paper the many properties of heusler compounds will first be introduced, then their successful application in metallic spintronic devices magnetic tunnel junctions will be described, followed by a discussion on their applications beyond metallic spintronics and their integration with the well established iiiv compound semiconductors and devices. As halfheusler compounds are promising candidates for environmentally friendly and lowcost thermoelectric materials, not only a high figure of merit and efficiency are necessary but also detailed knowledge of mechanical properties and thermal expansion is compulsory. Slaterpauling curve for full heusler compounds full heusler compounds hybridization between coco and mn in minority bands in co 2 mnsige i. In native states, these halfheusler compounds are identified as being topologically nontrivial semimetals, or nontrivial metals, or trivial insulators, which can be turned into insulating thin films on suitable substrates.
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