Anisotropy of phonon modes in spontaneously ordered GaInP{sub 2}

Journal Article · Fri Jun 15 04:00:00 EDT 2001 · Physical Review B

DOI:https://doi.org/10.1103/PhysRevB.63.235205· OSTI ID:40203619

Seong, M J; Mascarenhas, A; Olson, J M; Cheong, Hyeonsik M

The anisotropy associated with angular variation of the phonon wave vector q with respect to the ordering axis z{sup {prime}} of a spontaneously ordered GaInP{sub 2} with order parameter {eta}{congruent}0.46 is studied by carefully performing micro-Raman measurements in scattering geometries where q is either parallel or perpendicular to z{sup {prime}}. The LO mode at {similar_to}380cm{sup {minus}1} and the TO mode at {similar_to}330cm{sup {minus}1} exhibit distinct phonon frequency shifts of {minus}1.2cm{sup {minus}1} and +2.1cm{sup {minus}1}, respectively, as the angle {phi} between q and z{sup {prime}} varies from 0{degree} to 90{degree}. This small angular dispersion is explained on the basis of the bond-stiffening along the ordering axis with increasing order parameter {eta}, providing strong evidence for a small A{sub 1}-E splitting in comparison to the large LO-TO splitting for these modes. In addition, an even larger angular dispersion, +2.5cm{sup {minus}1}, for the vibrational mode at {similar_to}354cm{sup {minus}1} is observed. Two additional phonon modes, which have previously been labeled as missing to account for all nine Raman-active optical modes, are observed and experimentally identified with E(x) and E(y) tensors.

• Sponsoring Organization: (US)
• OSTI ID: 40203619
• Journal Information: Physical Review B, Journal Name: Physical Review B Journal Issue: 23 Vol. 63; ISSN 0163-1829
• Publisher: The American Physical Society
• Country of Publication: United States
• Language: English

Related Subjects

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS
ANISOTROPY
OPTICAL MODES
ORDER PARAMETERS
PHONONS
SCATTERING
VECTORS