Noncollinear magnetic structure in tetragonal heusler. Heusler alloys for spintronic devices will begin the morning of thursday, july 30th and at 3. In the recent decade, the family of heusler compounds has attracted tremendous scientific and technological interest in the field of spintronics. Antiferromagnetic heusler compounds for spintronics pub. The halfheusler compounds have eight valance electrons, including a large number of semiconductors with energy gaps vary in a wide range 9. Investigation of the structural competing and atomic ordering. Halfmetallic stability of the heusler alloys tizrirz z. Advancement in heusler compounds and other spintronics. Both fe 2 nisi and ni 2 fesi have the xa structure in cubic phase and they show metallic band structures and large magnetic moments greater than 3. They form the inverse cubic heusler structure with three distinct. Heteroepitaxial growth of tetragonal mn fe ga 0 x 1. For spintronic application, the magnetic heusler compounds and halfmetals, in particular, are of utmost interest.
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 attracted significant. This systematic study can provide a comprehensive reference for the further development of ti and zr based quarternay heusler compounds and even inspire other relative studies for the exploration of new. Tetragonal mnbased heusler for ultrahigh frequency. The free carrier spin polarization at the fermi level is an important property and is given by. Similar to halfheusler materials, this structure consists of four interpenetrating fcc sublattices, two of. Scope of tetragonal manganese based heusler alloys in context of. The structural competing and atomic ordering of the full heusler compounds fe 2 nisi and ni 2 fesi under uniform and tetragonal strains have been systematically studied by the firstprinciples calculation. Heusler compounds show high spin polarization in spintronic devices. Heusler compounds have been predicted to be halfmetallic possessing integer magnetic moments due to complete spin polarisation at the fermi level, a property highly desirable in spintronics. 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. Thin films of these materials have been shown to exhibit large pma for films grown. This class of heusler compounds offer a degree of flexibility which is lacking in binary and pseudobinary ferromagnetic. Transfer torque applications and its experimental realization j winterlik, s chadov, a gupta, v alijani, t gasi, k filsinger, b balke. Butler3,4, y 1department of electrical and computer engineering, university of virginia, charlottesville,va22904, usa.
Heusler compounds with perpendicular magnetic anisotropy. Compensated ferrimagnetic tetragonal heusler thin films for. The x atoms occupy the wyckoff position 8c 14, 14, 14, the y and the z atoms are located at 4a 0, 0, 0 and 4b 12, 12, 12, respectively. Lastly, the uniform and tetragonal strains have been accessed and their effects on the electronic and magnetic properties have been studied. Structural, elastic, electronic, magnetic and thermoelectric. In the present work, the elastic constants and derived properties of tetragonal heusler compounds were calculated using the high accuracy of the fullpotential linearized augmente. The magnetic heuslers with multiple magnetic sublattices are excellent candidates provide a perfect platform to for the design of anisotropic and acentric roomtemperature magnets 5.
Tetragonal heusler mn 3ge, the one similar to mn 3ga, is another interesting material. Tetragonal mnbased heusler compounds, mnga binary 1,2 and mncoga ternary 3, have attracted attentions for nano spintronics applications, such as spintransfertorque magnetic random access memory 4, since those have a small magnetization 5, large magnetic anisotropy 5, lowloss at highfrequency 6, and highelectronic spin. A dinner for workshop participants will be held on thursday evening. The new materials are quaternary limgpdsbtype compounds contained all atoms in the two parents heusler alloys. Heusler compounds are a large family of binary, ternary, and quaternary compounds that exhibit a wide range of properties of both fundamental and potential technological interest. Tetragonal heusler compounds for spintronics semantic. Casper, others, design scheme of new tetragonal heusler. The lowfield mt curves measured within the zerofieldcooled zfc and fieldcooled fc cycles are shown in fig. The three main prototypical heusler stoichiometric, chemically ordered structural types, namely half, regular, and inverse, are shown in figure 1. In comparison, mn 2 rhsn is a tetragonal heusler compound with moderate mca and a lattice mismatch of only 1. Wu1 1beijing national laboratory for condensed matter physics, institute of physics, chinese academy of.
The most prominent example is the combination of magnetism and exceptional transport properties in spintronic devices. The heusler compounds also exhibit good thermoelectric properties 1719 and. Since tetragonal heusler compounds have many potential applications in spintronics and. This observation, typical for the tetragonal polycrystalline ferrimagnetic heusler alloys, may result from a random orientation of the anisotropic crystallites 26. Jan 18, 2016 heusler alloy thin films with a distorted tetragonal structure have potential spintronics applications given their bulk perpendicular magnetic anisotropy.
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. The findings show that the ferromagnetic phase of type i atomic arrangement is. This is essentially due to their exceptional magnetic properties, which qualify them as promising functional materials in various datastorage devices, such as giantmagnetoresistance spin valves. The compounds investigated in these studies contained 3d elements exclusively on the x, x0, and y positions.
Some examples of tetragonal heusler compounds are mn3. Heusler compounds in devices for spintronic applications 37 6. These ternary intermetallic compounds were introduced by f. In general, the heusler compounds have face centered cubic crystal structures, which are either the fullheusler or the halfheusler structures with lattice parameters ranging from 5. These materials show a wide range of properties, but new properties are constantly being found. Introduction key to the successful development of spintransfer torque magnetic random access memory sttmram, one of the. Robust spingapless behavior in the newly discovered half. Tetragonal mnbased heusler compounds, mnga binary 1,2 and mncoga ternary 3, have attracted attentions for nanospintronics applications, such as spintransfertorque magnetic random access memory 4, since those have a small magnetization 5, large magnetic anisotropy 5, lowloss at highfrequency 6, and highelectronic spin. Highpressure investigations on the semiheusler compound. While the tetragonal alloys exhibit features attractive for stt applications high t c, strong pma, high spin polarization, low m s, the cubic systems represent a large class of 100% spin polarized halfmetallic heusler materials that robustly follow the slaterpauling rule similar to the co 2 yz compounds. Cubic heusler, tetragonal, and hexagonal heusler like alloys 3. In this article we highlight recent major developments in the field of.
Also, there could be various defects present in both structures, including disorder, antisite, swap and vacancy. To reduce the saturation magnetization, particular conditions such as specific substitutions or buffer layers are required. Halfmetallic heusler compounds have been the subject of numerous studies for their versatile properties and particularly for their potential applications in spintronics. The study of the structural, mechanical, and magnetoelctronic properties of tizrirz z al, ga, in quaternary heusler alloys was performed using fullpotential linearized augmented planewave fplapw method, based on the density functional theory dft with generalized gradient approximation gga. Noncollinear magnetic structure in tetragonal heusler materials.
Structure and properties of quaternary and tetragonal heusler compounds for. Cubic heusler, tetragonal, and hexagonal heuslerlike alloys 3. In recent years, hh compounds with hm properties have been widely reported 2123. Compensated ferrimagnetic tetragonal heusler thin films for antiferromagnetic spintronics roshnee sahoo 1, lukas wollmann 1, susanne selle 2, thomas hoche 2, benedikt ernst 1, adel kalache 1, chandra shekhar 1, nitesh kumar 1, stanislav chadov 1, claudia felser, stuart s. However, both tetragonal and cubic phases have their own importance for industrial as well as fundamental research.
However, several recent studies have found many heusler materials have tetragonal structure as the ground state, e. However, there are yet to be any reports of 100% spin polarisation experimentally. Investigation of the structural competing and atomic. On the other hand, several studies have demonstrated that a large number of heusler compounds have the tetragonal structure as the ground state 4,49,5155. Heusler in 1903 with the discovery of strong ferromagnetic properties of cu2mnal 1. The half heusler compounds have thermoelectrical properties. Normally, heusler compounds have highly ordered cubic crystal structures with different atomic ordering configurations. Tetragonal heusler compounds for spintransfer torque. Structural, electronic and magnetic properties of x2yz. Compensated ferrimagnetic tetragonal heusler thin films.
Nayak, journalieee transactions on magnetics, year20, volume49, pages682685. Computational investigation of halfheusler compounds for spintronics applications jianhua ma,1, vinay i. Heusler alloy thin films with a distorted tetragonal structure have potential spintronics applications given their bulk perpendicular magnetic anisotropy. Pdf magnetic heusler compounds claudia felser academia. While they have been known for a long time, 1 it is only in recent years that a wide range. With respect to the requirements of spin torque transfer stt materials, one the most promising materials families are the tunable tetragonal heusler compounds based on mn 2 yz y co,fe,ni,rh, z al, ga, sn. Highpressure investigations on the semiheusler compound cumnsb. In crystallography, the tetragonal crystal system is one of the 7 crystal systems. 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. Epitaxial thin films of inverse tetragonal mn2ptsn were synthesized and show lattice. Heusler in 1903 with the discovery of strong ferromagnetic properties of. Sugihara et al 30 report on structure and magnetic properties of mn 3ge compound epitaxial films exhibiting the high perpendicular magnetic anisotropy over 10merg cm. In this work, we have conducted detailed growth and characterization along with complementary.
Dec 11, 2012 it is important to emphasize that while tetragonal distortion is a necessary condition, it does not guarantee perpendicular magnetization in thin films as reported recently for the related tetragonal heusler compounds rh 2 yz. The key of spintronic devices using the spintransfer torque phenomenon is the effective reduction of switching current density by lowering the damping constant and the saturation magnetization while retaining strong perpendicular magnetic anisotropy. A critical study of the elastic properties and stability of. Apr, 2015 in mn 2heusler compounds, ferromagnetism might be metastable. Tetragonal heusler compounds for spintronics ieee xplore. Novel halfmetallic and spingapless heusler compounds. Index termsheusler compounds, magnetic properties, materials science, spin torque transfer, spintronics. The tetragonal phase of mn 3x rh x sn has been experimentally determined to be stable up to x 0. Influence of tetragonal distortion on the topological electronic structure of the half heusler compound laptbi from first principles x. Hegde,2 kamaram munira,3 yunkun xie,1 sahar keshavarz,3,4 david t. Towards to this direction, it was reported that the tetragonal phase of the mn 38. Compared to the convenient co2mnz heusler compounds 17,18, one co atom was substituted by rh.
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 half. Basics and prospective of magnetic heusler compounds. Plenary talks will be 40 minutes with 5 minutes for questions, and invited talks will be 30 with 5 minutes for questions and. This book gives an overview of the physics of heusler compounds ranging from fundamental properties of these alloys to their applications. Tetragonal heusler compounds for spintronics request pdf. 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. Tetragonal mnbased heusler for ultrahigh frequency spintronics.
Design scheme of new tetragonal heusler compounds for spin. Influence of tetragonal distortion on the topological. We performed densityfunctional theory calculations for 286 heusler compounds and identified 116 stable. Sitepreference, electronic, magnetic, and halfmetal.
Yet quaternary heusler compounds with interesting properties have not been investigated. Quaternary heusler compounds co2x rh x mnz zga, sn, sb. Request pdf tetragonal heusler compounds for spintronics with respect to the requirements of spin torque transfer stt materials, one the most promising materials families are the tunable. Heusler compounds form an intensively studied class of magnetic materials exhibiting novel physical properties due to strong spin polarization of charge carriers at the fermi level, high curie temperatures and martensite structural transitions, with possible application to spintronics and magnetic shape. To conclude, we present a tetragonal stoichiometric i4mmm heusler compound, pt 2 mnga, exhibiting roomtemperature longrange afm spiral order, which possesses a unique combination of properties for the heusler family of materials. Here, we give a comprehensive overview and a prospective on the magnetic properties of heusler materials. Mn2heusler compounds crystallize in the inverse structure and are characterized by antiparallel. The halfheusler compounds are composed with ternary xyz has a 1. The lattice parameters of the tetragonal cell are a 3. Highly reduced saturation magnetization in epitaxially. Computational investigation of halfheusler compounds for. Heusler alloys properties, growth, applications claudia. Complete spin gapless semiconductivity in equiatomic.
The materials with high spinpolarization, high curie temperature, and. In order to further design and develop novel quaternary heusler compounds to meet the demands of spintronics, we have used ab initio electronic structure calculations to identify these interesting compounds for spintronics applications. The extensive tunability of the heusler compounds through chemical substitutions and structural motifs makes the family especially interesting. Despite the potential importance of tetragonal heusler compounds for spintronic applications, there is still a lack of fundamental understanding. Devices based on spin dynamics in heusler compounds and oxides with low spin. With respect to the requirements of spin torque transfer stt materials, one the most promising materials families are the tunable tetragonal heusler compounds based on mn2yz yco,fe,ni,rh, zal, ga, sn. Recently, the enhancing of the thermoelectric performance of half heusler compounds are attracted the interest of nanotechnology applications.
The key differences between these various heusler compounds are highlighted in table 1. Recently, we find a good method to develop new materials with half metallicity is to combine two heusler alloys which have half metallic properties. The mismatch can be reduced by introducing larger atoms such as sn. All relaxations started from the c1 b structure with small displacements to avoid vanishing of the net force on each atom due to symmetry.
Here we present a theoretical and experimental study on the so far not reported quaternary heusler compounds corhmnz z dga, sn, sb. Structure and properties of quaternary and tetragonal. Structure and properties of quaternary and tetragonal heusler. We demonstrate relaxed epilayers of the tetragonal phase of cumnas grown on gaas. Request pdf tetragonal heusler compounds for spintronics with respect to the requirements of spin torque transfer stt materials, one the most promising. Spin gapless semiconductor nonmagnetic semiconductor transitions in fedoped ti2cosi. Tetragonal crystal lattices result from stretching a cubic lattice along one of its lattice vectors, so that the cube becomes a rectangular prism with a square base a by a and height c, which is different from a. These properties are attractive for the application to the next generation high density spintransfertorque stt magnetic random access memory sttmram.
The history of one of the most exciting material classes can be traced back to the year 1903 when fritz heusler discovered that an alloy with the composition cu 2 mnal behaves like a ferromagnet, although none of its constituent elements is magnetic by itself. 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. Apr, 2015 tetragonal heusler compounds with large magneto crystalline anisotropy can be easily designed by positioning the fermi energy at the van hove singularity in one of the spin channels. The effect of pressure and alloying on halfmetallicity of. Band jahnteller type structural instabilities of cubic mn2yz heusler compounds causing tetragonal distortions can be predicted by ab initio band. Origin of the tetragonal ground state of heusler compounds. G6g8 and gaps of the lnyz heusler family calculated with fully relativistic linear muffin orbitals method vs. 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 applications. Simple rules for the understanding of heusler compounds. Heusler compounds with perpendicular magnetic anisotropy and.
Films of the mnbased tetragonal heuslerlike alloys, such as mn ga, exhibit a large perpendicular magnetic anisotropy pma, small damping constant, small saturation magnetization and large spin polarizations. Journal of optoelectronics and advanced materials vol. In analogy to the iamnv compounds, all nearest neighbours in the tetragonal cumnas. Structure and properties of quaternary and tetragonal heusler compounds for spintronics and spin transfer torque applications. Recent advances in novel materials for future spintronics mdpi.
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