Europhys. Lett.
Volume 47, Number 3, August 1999
Page(s) 378 - 383
Section Condensed matter: electronic structure, electrical, magnetic and optical properties
Published online 01 September 2002
DOI: 10.1209/epl/i1999-00399-6

Europhys. Lett, 47 (3), pp. 378-383 (1999)

Magnetic phase transitions in $\rm Fe_{72}Pt_{28}$ Invar compound studied by high-pressure X-ray magnetic circular dichroism and X-ray diffraction

S. Odin 1, F. Baudelet 1, Ch. Giorgetti 1, E. Dartyge 1, J. P. Itié 2, A. Polian 2
J. C. Chervin 2, S. Pizzini 3, A. Fontaine 3 and J. P. Kappler 4

1 LURE, Bât 209D, Centre Universitaire Paris Sud - 91405 Orsay Cedex, France
2 Physique des Milieux Condensés, Université Paris VI - BP 77, 75252 Paris 05, France
3 Laboratoire de Magnétisme Louis Néel, CNRS BP 166
38042 Grenoble Cedex 9, France
4 IPCMS, 23 rue du Loess - 67037 Strasbourg Cedex, France

(received 22 June 1998; accepted in final form 2 March 1999)

PACS. 78.20Ls - Magnetooptical effects.
PACS. 62.50${\rm +p}$ - High-pressure and shock-wave effects in solids and liquids.
PACS. 81.30Bx - Phase diagrams of metals and alloys.


X-ray magnetic circular dichroism (XMCD) measurements have been performed under high pressure and used to study the disordered $\rm Fe_{72}Pt_{28}$ Invar alloy. The well-known high spin to low spin state transition is observed at 4 GPa. In addition, XMCD evidences a second transition to the nonmagnetic phase at high pressure in the disordered alloy. This result is made unambiguous by comparison to the ordered alloy whose hysteresis cycle of the phase transitions is dramatically different from the disordered alloy. The pressure-dependent collapse of the Curie temperature is the dominant mechanism for reducing the magnetization only in the ordered alloy.


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