SPIN-DEPENDENT RAMAN SCATTERING FROM PHONONS IN MAGNETIC SEMICONDUCTORS AND INSULATORS

(1)

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SPIN-DEPENDENT RAMAN SCATTERING FROM PHONONS IN MAGNETIC SEMICONDUCTORS

AND INSULATORS

G. Güntherodt, R. Merlin, G. Benedek, W. Bauhofer

To cite this version:

G. Güntherodt, R. Merlin, G. Benedek, W. Bauhofer. SPIN-DEPENDENT RAMAN SCATTERING

FROM PHONONS IN MAGNETIC SEMICONDUCTORS AND INSULATORS. Journal de Physique

Colloques, 1980, 41 (C5), pp.C5-241-C5-241. �10.1051/jphyscol:1980540�. �jpa-00219975�

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JOURNAL DE PHYSIQUE Colloque CS, suppltfment au n " 6, Tome 41, juin 1980, page ~ 5 - 2 4 1

SPIN-DEPENDENT RAMAN S C A T T E R I N G FROM PHONONS I N M A G N E T I C SEMICONDUCTORS AND I N S U L A T O R S

+ ++

G. Giintherodt, R. Merlin, G. Benedek , and W. Bauhofer.

M a x - P l a n c k - I n s t i t u t f i i r F e s t k 8 r p e r f o r s c h u n g , 7 0 0 0 S t u t t g a r t 8 0 , F e d e r a l R e p u b l i c

of Germany.

Extended abstract.-The spin-dependent Raman

scattering (RS) from phonons has been in- References vestigated in several rare earth and tran-

sition metal compounds with respect to the /1/ Merlin, R., Zeyher,R., and Giintherodt spin-dependent electron-phonon coupling G., Phys. Rev. Lett.

2

( 1 9 7 7 ) 1215.

mechanism. At present three different cases ^/2/ Giintherodt. G., J. Magnetism. and Magnet. Mat.

11

( 1 9 7 9 ) 3 9 4 .

can be distinguished : /3/ Ghtherodt, G., Merlin, R., and GrUn-

1 ) In europium chalcogenides with the 4f berg, P., Phys. Rev; B

20

⁽¹⁹⁷⁹⁾

states as initial states in RS a sirnulta- 2 8 3 4 . neous excitation of the spin and phonon

systems is possible via spin-orbit coupling in the excited intermediate state1. The scattering cross section is proportional to the spin correlation function and results in a) spin-disorder induced phonon

-

^zero

frequency spin excitations in the parama- gnetic phase, b) phonon-magnon excitations in the ferromagnetic phase and c) q f 0

phonon scattering induced by magnetic

"Bragg" scattering from spin Superstructures in the antiferromagnetic

2) The previously believed spin-dependent RS in Cd-Cr spinels is due to resonant RS associated with interband transitions undergoing exchange splittings, which fol- low a spin correlation function for tempe- ratures below the ordering temperature.

3 ) Most recent experiments on the antifer-

rornagnetic insulator VJ2 show for the first time for a transition metal compound zone boundary phonon RS induced by magnetic

"Bragg" scattering at the antiferromagnetic spin superstructure

'.

The simultaneous spin-phonon excitations occur via modula- tion of the exchange interactiorsbetween V ions by phonons of selected normal mode coordinates.

+ Present address: University of Illinois, Urbana- -Champaign, USA

++

Permanent address: GNSM del CNR, Universita di Milano , ^Italy.

/4/ Zeyher, R., and Kress, W., Phys. Rev.

B

-

2 0 ( 1 9 7 9 ) 2 6 5 0 .

/ 5 / Steigmeier, E.F., and Harbeke,G.,

Phys. Cond. Matt.

12

( 1 9 7 0 ) 1.

/ 6 / Suzuki, N., and Kamimura,H., 3. Phys.

Sot-Japan

35

( 1 9 7 3 ) 9 8 5 .

/ 7 / Iliev II., Giintherodt, G,, and Pink H.,

Solid State Commun.

27

( 1 9 7 8 ) 8 6 3 . /8/ Giintherodt. G., Bauhofer,W.. and

Benedek,G., Phys. Rev. Iiett'.

3

( 1 9 7 9 ) 1 4 2 7 .

Article published online by EDP Sciences and available at http://dx.doi.org/10.1051/jphyscol:1980540