Valence values of the cations in selenospinel

H.-J. Noh; J.-S. Kang; S. S. Lee; G. Kim; S.-W. Han; S.-J. Oh; J.-Y. Kim; H.-G. Lee; S. Yeo; S. Guha; S.-W. Cheong

doi:10.1209/0295-5075/78/27004

All issues

Volume 78 / No 2 (April 2007)

EPL, 78 2 (2007) 27004

Abstract

Issue		EPL Volume 78, Number 2, April 2007


Article Number		27004
Number of page(s)		6
Section		Condensed Matter: Electronic Structure, Electrical, Magnetic and Optical Properties
DOI		https://doi.org/10.1209/0295-5075/78/27004
Published online		29 March 2007

EPL, 78 (2007) 27004

Valence values of the cations in selenospinel $\chem{Cu(Cr,Ti)_2Se_4}$

H.-J. Noh¹^,2^,3, J.-S. Kang⁴, S. S. Lee⁴, G. Kim⁴, S.-W. Han², S.-J. Oh², J.-Y. Kim⁵, H.-G. Lee⁵, S. Yeo³, S. Guha³ and S.-W. Cheong³

¹ Department of Physics, Chonnam National University - Gwangju 500-757, Korea
² School of Physics & Center for Strongly Correlated Materials Research, Seoul National University - Seoul 151-742, Korea
³ Department of Physics & Astronomy and Rutgers Center for Emergent Materials - Piscataway, NJ 08854, USA
⁴ Department of Physics, The Catholic University of Korea - Puchon 420-743, Korea
⁵ Pohang Accelerator Laboratory, Pohang University of Science and Technology - Pohang 790-784, Korea

Corresponding author: ffnhj@chonnam.ac.kr

Received: 18 January 2007
Accepted: 4 March 2007

Abstract

A long-standing issue about the Cu valency in selenospinel CuCr₂Se₄ was investigated by soft X-ray absorption spectroscopy (XAS) and magnetic circular dichroism (XMCD). Using the sensitivity of XAS and XMCD to the valence value of transition metal ion and its local symmetry, we checked the valence value of each cation in selenospinel CuCr_xTi $_{2-x}$ Se₄ ( $x= 1.0$ , 1.1, 1.5, and 2.0) and obtained spectroscopic evidence that a small amount of the Cu cation changes the valency from Cu(I) to Cu(II) as the Cr concentration increases from 1.0 to 2.0. Dependence of the Cu(II) concentration and the mean field magnetic exchange energy on the Cr concentration suggests the Cu d-hole could play a crucial role in the intriguing magnetic/electrical properties of CuCr₂Se₄.

PACS: 71.20.Be – Transition metals and alloys / 78.70.Dm – X-ray absorption spectra

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