First-principles study of structural, magnetic, and electronic properties of small Fe-Rh alloy clusters

Mokkath, Junais Habeeb; Pastor, G.

doi:10.1103/physrevb.85.054407

Cited by 43 publications

(20 citation statements)

References 51 publications

(43 reference statements)

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“…This fact opens the possibility for a wide range of technological applications, such as magnetic storage [7][8][9][10], and heterogeneous catalysis [2,[11][12][13][14]. This possibility, along with the novel and interesting properties found on those systems, motivated a large number of experimental and theoretical studies [15][16][17] focusing on binary TM clusters, such as PtPd [18,19], PdIr [20], PtNi [21], PtRh [22], FeRh [10,23], and PtCu [24][25][26][27][28], with the aim to understand the behaviour of their physical and chemical properties as a function of the number of atoms, compositions, structure, and charge states.…”

Section: Introductionmentioning

confidence: 99%

Structural formation of binary PtCu clusters: A density functional theory investigation

Chaves

Rondina

Piotrowski

et al. 2015

Computational Materials Science

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Section: Introductionmentioning

confidence: 99%

Structural formation of binary PtCu clusters: A density functional theory investigation

Chaves

Rondina

Piotrowski

et al. 2015

Computational Materials Science

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“…Strained thin films [13,14] showed traces of a FM phase down to 300 K, while ab initio calculations predicted FM down to 0 K for a Rh-terminated 9 ML FeRh(001) film [15] and for 8-atom FeRh clusters [16]. Indeed, since nanosized crystals may present significantly different interatomic distances and unit cell distortions with respect to bulk [17,18], a fundamentally modified magnetic phase diagram can be expected for FeRh nanocrystals.…”

mentioning

confidence: 99%

Low Temperature Ferromagnetism in Chemically Ordered FeRh Nanocrystals

et al. 2013

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In sharp contrast to previous studies on FeRh bulk, thin films, and nanoparticles, we report the persistence of ferromagnetic order down to 3 K for size-selected 3.3 nm diameter nanocrystals embedded into an amorphous carbon matrix. The annealed nanoparticles have a B2 structure with alternating atomic Fe and Rh layers. X-ray magnetic dichroism and superconducting quantum interference device measurements demonstrate ferromagnetic alignment of the Fe and Rh magnetic moments of 3 and 1 B , respectively. The ferromagnetic order is ascribed to the finite-size induced structural relaxation observed in extended x-ray absorption spectroscopy. DOI: 10.1103/PhysRevLett.110.087207 PACS numbers: 75.30.Kz, 75.75.Cd, 81.07.Bc Iron-rhodium alloys exhibit competing ferromagnetic (FM) and antiferromagnetic (AFM) phases with transition temperatures close to ambient for nearly equiatomic composition and body-centered-cubic (bcc) CsCl-like B2 structure. The competition between the two magnetic orders of FeRh holds great potential in spintronics and heat assisted magnetic recording [1,2]. Moreover, the peculiar bulk FeRh magnetic phase diagram enables its use as active material in heat pumps and refrigerators [3][4][5].At ambient conditions, bulk B2 FeRh is a G-type AFM with a total magnetic moment on the iron atoms of 3:3 B and no appreciable moment on the rhodium atoms [6][7][8]. Above the transition temperature of 370 K, the atomic moments of Fe and Rh are ferromagnetically aligned and take on total values of 3.2 and 0:9 B , respectively [6][7][8]. While it has long been known that the bcc unit cell volume expands by % 1% upon transforming to FM order [9], recent experiments suggest that distortions of the bcc structure may occur [10]. Given the itinerant character of the 3d electrons, the coupling between crystallographic and magnetic order in this system is both rich and very delicate as demonstrated by the theoretical challenge to model the system [11], as well as by recent pump-probe experiments focusing on ultrafast magnetization control [12].Finite-size systems of this alloy have received particular attention by their potential to stabilize the FM phase at room temperature and below. Strained thin films [13,14] showed traces of a FM phase down to 300 K, while ab initio calculations predicted FM down to 0 K for a Rh-terminated 9 ML FeRh(001) film [15] and for 8-atom FeRh clusters [16]. Indeed, since nanosized crystals may present significantly different interatomic distances and unit cell distortions with respect to bulk [17,18], a fundamentally modified magnetic phase diagram can be expected for FeRh nanocrystals. However, the first experiments on chemically synthesized FeRh nanoparticles (NPs) failed to evidence low temperature stability of the FM phase. Most notably, they raised important questions, such as partial B2 ordering, elemental segregation, and coalescence upon annealing [19][20][21].In this Letter, we demonstrate the persistence of FM order down to below 3 K in size-selected FeRh nanocrystals with a mean d...

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“…Similar 3d to 4d charge transfers have been found in FeRh clusters. 51 Concerning the spatial distribution of the spin polarization, we observe that more than 95% of the total magnetization originates in the WS spheres of the atoms, when the Co content is important. This can be verified by comparing the results forμ andμ WS in the Table II.…”

Section: A Corh Clusters With N = 43 Atomsmentioning

confidence: 82%

Local and chemical environment dependence of the magnetic properties of CoRh core-shell nanoparticles

2013

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The ground-state magnetic properties of Co x Rh 1−x nanoparticles having sizes in the range of 0.8-2 nm (N = 43 and 273 atoms) and Co concentrations x ≈ 0, 0.25, 0.5, 0.75, and 1 are investigated in the framework of density-functional theory by using a fixed-moment method. Electron correlation effects are explored by comparing the results of the local spin-density and generalized-gradient approximations to the exchange and correlation functional. The role of chemical order on the magnetic behavior is investigated by considering a variety of core-shell atomic arrangements with nearly spherical CoRh interfaces. A local relaxation of the cluster geometry is performed by taking face-centered cubic structures as starting configurations. All considered Co x Rh 1−x clusters are found to be magnetic with an average spin moment per CoRh unit that is larger than in macroscopic alloys having similar concentrations. This is a consequence of both, the enhancement of the Co moments and the occurrence of important induced Rh moments, which couple parallel to the Co moments. The distribution of the local magnetic moments within the clusters is found to depend strongly on the local and chemical environment of the atoms. In particular, the Rh moments show a nontrivial dependence as a function of the distance to the CoRh interface. The results for the local magnetic moments are correlated to the electronic densities of states, which reflect the concentration and chemical-order dependence of the cluster electronic structure. Finally, the effects of coating and of the 3d-4d interface are analyzed by comparing the magnetic behaviors of core-shell particles with those of the corresponding pure Co and Rh cores.

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First-principles study of structural, magnetic, and electronic properties of small Fe-Rh alloy clusters

Cited by 43 publications

References 51 publications

Structural formation of binary PtCu clusters: A density functional theory investigation

Structural formation of binary PtCu clusters: A density functional theory investigation

Low Temperature Ferromagnetism in Chemically Ordered FeRh Nanocrystals

Local and chemical environment dependence of the magnetic properties of CoRh core-shell nanoparticles

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