One of the first strategies for enhancing zt values not only for hh materials. This database provides information on three families of heusler alloys, full heuslers a 2 bc, half heuslers abc and inverse heuslers abac. 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. For each of the 378 potential half heusler compounds, we calculate its electronic and magnetic structure, stability against structural distortion, formation energy, and thermodynamic phase stability. Computational investigation of inverse heusler compounds for. Crystal structure, composition and heat treatment were found. Simple rules for the understanding of heusler compounds. Heusler compounds are constituted by a significant fraction of the elements in the periodic table. Gdptbi and ndptbi belong to the heusler family of compounds and are conventional antiferromagnets below 9 and 2. In the last decade, the halfheusler compounds have attracted significant research attention for their thermoelectrics properties. Among the family of half heusler compounds, the weyl semimetal gdptbi is significant because it exhibits a chiral anomaly 14, a planar hall effect 15, a linear optical conductivity 16.
Recent advances in nanostructured thermoelectric halfheusler compounds. Especially heusler compounds as half metallic ferromagnetic and topological insulators are important in condensed matter science due to their potential in. 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. Additionally, an inverse design by computational methods considering special requirements, e. Professor ctirad uher, chair assistant professor emmanouil kioupakis associate professor lu li. Electronic structure and physical properties of heusler compounds. Using a combination of molecular beam epitaxy, core. The search for stable halfmetallic ferromagnets and ferromagnetic semiconductors with curie. 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. Pdf recent advances in thermoelectric performance of. Here, we report an energysaving preparation route using a domestic microwave oven, reducing the reaction time significantly from more than a week to one minute. In addition, a series of sndoped fenbsb compounds was prepared in accordance with the optimal. Recent advances in nanostructured thermoelectric halfheusler. Halfheusler alloys as promising thermoelectric materials by.
Ternary semiconducting or metallic halfheusler compounds with an atomic composition 1. The generalized gradient approximation is used to model exchangecorrelation effects. The semiconducting heusler compounds can be identified by the number of valence electrons. Pdf recent advances in nanostructured thermoelectric half. The halfheusler compound cotisb, which is a semiconductor, may be thought of as a zincblende sp. First principles electronic structure and magnetic properties of. The latter compounds are often called half or semiheusler alloys, while the l21 compounds are referred to as fullheusler alloys. Novel halfmetallic and spingapless heusler compounds yunlong jin, ph. An enormous class of double halfheusler compounds with.
The two structures are closely related with vacant cite. May 17, 2016 half heusler compounds based on xnisn and xcosb x ti, zr or hf have rapidly become important thermoelectric materials for converting waste heat into electricity. Semiconducting half heusler compounds can be understood as stuffed variants of the binary zinc blende semiconductor and by simple electron counting. Mnisn m ti, zr, and hf half heusler hh compounds are widely studied ntype thermoelectric te materials for power generation. Recently, a new material property of halfheusler compounds was predicted based on electronic structure calculations. Our results show that the z 2 topological order is due to a single band inversion at the. Investigations of the electronic structure of halfheusler compounds were carried out, to gain an understanding of their physical properties.
Heusler hh compounds are currently promising thermoelectric te materials due to their outstanding performance. Investigations of the electronic structure of half heusler compounds were carried out, to gain an understanding of their physical properties. Improving the thermoelectric properties of half heusler. Thermal conductivity of halfheusler compounds from first. An enormous class of double half heusler compounds with. Dear colleagues, the increasing interest in heusler and halfheusler compounds, since the first discovery of the 1 st cu 2 mnal heusler compound by the german scientist friedrich heusler in 1903, passing 100,000 publications in 2017, with more than 1500 reported compounds, is due to their high potential for a wide variety of.
For each of the 378 potential halfheusler compounds, we calculate its electronic and magnetic structure, stability against structural distortion, formation energy, and thermodynamic phase stability. Halfheusler phases and nanocomposites as emerging highzt thermoelectric materials volume 26 issue 22 s. Halfheusler compounds are an impressive class of materials with a huge potential for different applications such as future energy applications and for spintronics. Sintering temperature can affect relative density, and consequently, improve te performance. Home search collections journals about contact us my iopscience halfheusler compounds. Heusler and halfheusler compounds are usually prepared by conventional solid state methods involving arcmelting and annealing at high temperatures for an extended period of time.
Fecher, and claudia felser abstract spintronics is a multidisciplinary. Sellmyer this thesis is devoted to experimental studies of heusler compounds cofecral. Yz quaternary heusler compounds crystallize in the limgpdsntype crystal structure 10, 11 with f43m symmetry. Density functional theory calculations we perform all calculations using densityfunctional. New heusler compounds and their properties benjamin balke, gerhard h. Pdf magnetic heusler compounds claudia felser academia. Especially heusler compounds as halfmetallic ferromagnetic and topological insulators are important in condensed matter science due to their potential in. Half heusler compounds stuffed zns are candidates for thermoelectric applications and for diluted semiconductors nanostructured heuslers are need for low thermoconductivity heusler compounds are half metals with high curie temperatures.
May 06, 2019 heusler alloys have been a significant topic of research due to their unique electronic structure, which exhibits half metallicity, and a wide variety of properties such as magnetocalorics, thermoelectrics, and magnetic shape memory effects. Half he siham ouar optimizing the thermo heusler all zt 0. Oct 15, 2014 ternary semiconducting or metallic half heusler compounds with an atomic composition 1. We present the results of electrical resistivity and hall effect measurements on single crystals of hfnisn, tiptsn, and tinisn. We report superconductivity and magnetism in a new family of topological semimetals, the ternary halfheusler compound r pdbi r. New ferromagnetic, semiconducting, or even topologicalinsulating heusler and halfheusler. Halfhe siham ouar optimizing the thermo heusler all zt 0. Structural, electronic and magnetic properties of x2yz. To corroborate the present results, the prototype hightemperature thermoelectric modules with eight np halfheusler couples were assembled fig. Rapid microwave preparation of thermoelectric tinisn and. Herein, the optimal sintering temperature and pressure of these compounds were determined.
Novel halfmetallic and spingapless heusler compounds. Pdf halfheusler compounds are an impressive class of materials with a huge potential for different applications such as future energy applications. The halfheusler compounds can be thought of as having only half of the nacl tetrahedral sites filled by x or as an xz zincblende lattice with the octahedral sites filled with y. Semiconducting and half metallic heusler compounds for. Halfheusler alloys as promising thermoelectric materials by alexander a. An enormous class of double halfheusler compounds with low. C1b structure can be obtained from l21 one by replacing the half of.
Topological electronic structure in halfheusler topological. The effect of pressure and alloying on halfmetallicity of. The half heusler compounds can be thought of as having only half of the nacl tetrahedral sites filled by x or as an xz zincblende lattice with the octahedral sites filled with y. Anomalous hall effect in weyl semimetal halfheusler. Since 20, the verifiable zt of halfheusler compounds has risen from 1 to near 1. Heusler compounds, zrnisn and nbfesb, are identified as promising high. Heusler alloys properties, growth, applications claudia. Basics and prospective of magnetic heusler compounds. Dear colleagues, the increasing interest in heusler and half heusler compounds, since the first discovery of the 1 st cu 2 mnal heusler compound by the german scientist friedrich heusler in 1903, passing 100,000 publications in 2017, with more than 1500 reported compounds, is due to their high potential for a wide variety of. Study of thermoelastic and lattice dynamics properties of half. Fullheusler compounds with l 2 1type structure total number of valence electrons per formula unit vec z t 24 a simple rule with number of valence electrons in principles semiconductors in reality semimetals halfheusler compounds with c b 1type structure total number of valence electrons per formula unit vec z t 18. Engineering halfheusler thermoelectric materials using zintl.
The metallic properties of these compounds were studied using magnetization, as well mossbauer detailed guide measurements. Structural stability of nicontaining halfheusler compounds. The crystal structure of a typical halfheusler hh compound abc. Half heusler alloys as promising thermoelectric materials by alexander a. As listed in table 1, the magnetic moment per formula unit and the bandgap d are calculated to be approximately 3. The band structures and transport properties of half heusler compounds nbfesb and nbrusb were studied using ab initio calculations and the boltzmann transport equation with constant scattering time approximation csta. Halfheusler phases and nanocomposites as emerging highzt. The mg and ag atoms form a rock salt b1 structure, while the as and either the mg or ag atoms form a zincblende b3 structure. Page a dissertation submitted in partial fulfillment of the requirements for the degree of doctor of philosophy physics in the university of michigan 2017 doctoral committee. Structural, elastic, electronic, magnetic and thermoelectric. Band structures and transport properties of halfheusler. A simple electron counting model for halfheusler surfaces. New materials must be found for satisfying the different types of requirement. Heusler compounds are a class of ternary intermetallics, including full heusler x2yz with the l21 structure, and half heusler xyz with c1b.
Heusler compounds are a ripe platform for discovery and manipulation of emergent properties in topological and magnetic heterostructures. Chapter 2 new heusler compounds and their properties. We demonstrate successful application of firstprinciplesbased thermal conductivity calculation on halfheusler compounds that are promising, environmentally friendly thermoelectric materials. Recently, another family of heusler compounds known as quaternary heusler alloys with chemical formula of xx. Among half heusler compounds, tinisn and ticosb belong to the group of nonmagnetic and semiconducting materials, mnnisb, however, is a half metallic ferromagnet. Nicontaining halfheusler compounds, nimp, with m 5sc,ti,zr,hf and p5sn,sb form in the mgagas structure type space group. Computational investigation of inverse heusler compounds. Recent advances in nanostructured thermoelectric half heusler compounds. The band structures and transport properties of halfheusler compounds nbfesb and nbrusb were studied using ab initio calculations and the boltzmann transport equation with constant scattering time approximation csta. Electronic structure of the prnibi halfheusler system based.
The latter compounds are often called half or semi heusler alloys, while the l21 compounds are referred to as full heusler alloys. Semiconducting behavior is observed in each case, involving the transport of a small number of highly compensated. Enhancing thermoelectric performance of tinisn halfheusler. Half heusler xyz compounds have a noncentrosymmetric cubic structure with \f\bar43m\ space group, where x and y are transition metal or re elements, and z is a main. Most studies focus on zr and hfbased compounds due to their high thermoelectric performance. Among the family of halfheusler compounds, the weyl semimetal gdptbi is significant because it exhibits a chiral anomaly 14, a planar hall. Among halfheusler compounds, tinisn and ticosb belong to the group of nonmagnetic and semiconducting materials, mnnisb, however, is a halfmetallic ferromagnet. This book gives an overview of the physics of heusler compounds ranging from fundamental properties of these alloys to their applications.
Improving the thermoelectric properties of half heusler compounds di wu march 31th, 2011. Halfheusler compounds possess robust mechanical properties and excellent thermal stabilities, and have been recently recognized as one of the most promising candidates for high temperature thermoelectric power generation. Heusler and half heusler compounds are usually prepared by conventional solid state methods involving arcmelting and annealing at high temperatures for an extended period of time. Here the compositional adjustment is systematically studied in v 1. In halfmetallic heusler compounds, the top edge and bottom edge of the highest and the lowest, respectively, occupied spindown bands, touch the fermi level. Zr, hf compounds under pressure by means of first principles calculations. Recently, a new material property of half heusler compounds was predicted based on electronic structure calculations. The increasing interest in heusler and halfheusler compounds, since the first discovery of the 1 st cu 2 mnal heusler compound by the german scientist friedrich heusler in 1903, passing 100,000 publications in 2017, with more than 1500 reported compounds, is due to their high potential for a wide variety of applications in future energy fields including thermoelectrics, solar cells and spintronics. Halfheusler xyz compounds have a noncentrosymmetric cubic structure with \f\bar43m\ space group, where x and y. Half heusler compounds are an impressive class of materials with a huge potential for different applications such as future energy applications and for spintronics.
Novel half metallic and spingapless heusler compounds yunlong jin, ph. The most studied ones are the rnisntype halfheusler compounds, where r. The most studied ones are the rnisntype halfheusler compounds, where r represents refractory metals hf, zr, and ti. Titanium doping to enhance thermoelectric performance of 19. In addition, a series of sndoped fenbsb compounds was prepared in. Heusler compounds are magnetic intermetallics with facecentered cubic crystal structure and a composition of xyz half heuslers or x 2 yz fullheuslers, where x and y are transition metals and z is in the pblock. Nbcosb with nominal 19 valence electrons, which is supposed to be metallic, is recently reported to also exhibit thermoelectric properties of a heavily doped n. Halfheusler compounds based on xnisn and xcosb x ti, zr or hf have rapidly become important thermoelectric materials for converting waste heat into electricity. Mnisn m ti, zr, and hf halfheusler hh compounds are widely studied ntype thermoelectric te materials for power generation. In these applications, the surfaces and interfaces are critical to performance.
Heusler compounds in devices for spintronic applications 37 6. Nicontaining half heusler compounds, nimp, with m 5sc,ti,zr,hf and p5sn,sb form in the mgagas structure type space group. One recent prominent example of a binary semiconductorhalf heusler compound analogue are the topological insulators. Sep 11, 2018 gdptbi and ndptbi belong to the heusler family of compounds and are conventional antiferromagnets below 9 and 2.
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