Pressure effect on the Curie temperature and thermal expansion of CrTe

Ohta, Satoru; Kanomata, T.; Kaneko, T.; Yoshida, Hiroshi

doi:10.1088/0953-8984/5/17/010

Cited by 32 publications

(23 citation statements)

References 10 publications

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“…This conjecture is consistent with ab initio computations [35] predicting zinc-blende CrTe to be a ferromagnetic half-metal as well as with experimental results for CrTe in a bulk NiAs-type structure for which T m ≡ T C = 340 ± 10 K [36]. Within this scenario, for small ferromagnetic nanocrystals we expect T B < T It is, therefore, legitimate to suppose that coherent nanocrystals with a large concentration of magnetic constituent account for high apparent Curie temperatures detected in a number of DMS and DMO.…”

Section: Nonuniform Ferromagnetic Dms -Chemicalsupporting

confidence: 91%

High Temperature Ferromagnetism and Nano-Scale Phase Separations in Diluted Magnetic Semiconductors and Oxides

Dietl

2007

Acta Phys. Pol. A

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In this paper the present understanding of the origin of ferromagnetic response that has been detected in a number of diluted magnetic semiconductors and diluted magnetic oxides at room temperature is outlined. It is argued that in these systems, owing to a typically small solubility of magnetic ions, crystallographic or chemical phase separation into regions with a large and a small concentration of magnetic component takes place. The ferromagnetic signatures then come from the regions with a large concentration of magnetic ions, which show non-zero spontaneous magnetization up to the blocking temperature, whose magnitude is proportional to the nanocrystal volume and magnetic anisotropy. Novel methods enabling a control of nano-assembling of magnetic nanocrystals in non-conducting matrices as well as possible functionalities of these spatially modulated magnetic systems are described. We also discuss phase separations into paramagnetic and ferromagnetic regions, which are driven by the Anderson-Mott localization and/or competing ferromagnetic and antiferromagnetic interactions. Finally, the question whether the high temperature ferromagnetism is possible in materials without magnetic ions is addressed.

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Section: Nonuniform Ferromagnetic Dms -Chemicalsupporting

confidence: 91%

High Temperature Ferromagnetism and Nano-Scale Phase Separations in Diluted Magnetic Semiconductors and Oxides

Dietl

2007

Acta Phys. Pol. A

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“…These remarkable observations can readily be interpreted under the assumption that the relevant magnetic nanoparticles are built of a metallic zinc-blende CrTe or Cr-rich (Zn,Cr)Te characterized by T m ≈ 320 K and by the lattice constant imposed by a paramagnetic semiconductor host, either ZnTe or (Zn,Cr)Te with a rather small Cr concentration. This conjecture is consistent with ab initio computations (Zhao and Zunger, 2005) predicting zinc-blende CrTe to be a ferromagnetic half-metal as well as with experimental results for CrTe in a bulk NiAs-type structure for which T m ≡ T C = 340 ± 10 K (Ohta, Kanomata, Kaneko and Yoshida, 1993). Within this scenario, for small ferromagnetic nanocrystals we expect T B < T (app) C < T C , T B being proportional to a mean nanoparticle volume V , T B ≈ KV /(25k B ), where K is the density of the magnetic anisotropy energy.…”

Section: Spinodal Decompositionsupporting

confidence: 91%

Diluted Ferromagnetic Semiconductors—Theoretical Aspects

Dietl

2007

Handbook of Magnetism and Advanced Magnetic Materials

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This chapter reviews theoretical understanding of ferromagnetic response that has been detected in diluted magnetic semiconductors (DMS). Particular attention is paid to those ferromagnetic DMS in which no precipitation of other crystallographic phases has been observed. It is argued that these materials can be divided into three categories. The first consists of (Ga,Mn)As, heavily doped p‐(Zn,Mn)Te, and related compounds. In these solid solutions, the theory built on p–d Zener's model of hole‐mediated ferromagnetism and on either the Kohn‐Luttinger kp theory or the multiorbital tight‐binding approach describes qualitatively, and often quantitatively, thermodynamic, micromagnetic, optical, and transport properties. Moreover, the understanding of these materials has provided a basis for the development of novel methods enabling magnetization manipulation and switching. To the second group, belong compounds in which a competition between long‐range ferromagnetic and short‐range antiferromagnetic interactions and/or the proximity of the localization boundary lead to an electronic nanoscale phase separation that results in characteristics similar to colossal magnetoresistance oxides. Finally, in a number of compounds a chemical nanoscale phase separation into the regions with small and large concentrations of the magnetic constituent is present. Methods of controlling the spinodal decomposition and possible functionalities of these systems are outlined.

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“…In m-Cr 5 Te 8 the angles Cr-Te-Cr come closer to 90 thus supporting ferromagnetic superexchange to become more effective. We note that depending on the nature of the dominating exchange mechanism an anomalous thermal expansion or contraction of the lattice parameters as well as of the unit cell volume has been reported for different Cr tellurides and selenides [43][44][45][46][47][48][49].…”

Section: Article In Pressmentioning

confidence: 99%