Abstract
We report on the observation of a magnetic-field-tunable negative thermal expansion in layered oxyselenides. The crystalline unit cell of BiOCuSe contracts upon warming from 180 to 200K. This effect can be enlarged by the application of a magnetic field. Negative thermal expansion occurs at higher temperatures to appear between 240 and 260K, with a larger effect, in the 4% Cu-deficient BiOCu0:96Se. The negative thermal expansion is connected to the structural distortion that occurs in the ferromagnetic state, involving both magnetic electrons and conduction charges that are linked through weak interlayer ionic Bi-Se bonding and strong in-plane covalent Se-Cu bonding. The distortion can be strengthened by the application of a magnetic field.
Original language | English |
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Article number | 094705 |
Journal | Journal of the Physical Society of Japan |
Volume | 82 |
Issue number | 9 |
DOIs | |
State | Published - Sep 2013 |
Keywords
- Charge transfer
- Negative thermal expansion
- Oxysulphide