Temperature-dependent Raman and x-ray studies of the spin-ice pyrochlore Dy2Ti2O7 and nonmagnetic pyrochlore Lu2Ti2O7

被引：75

作者：

Saha, Surajit ^{[1
]}

Singh, Surjeet ^{[2
]}

Dkhil, B. ^{[3
]}

Dhar, S. ^{[4
]}

Suryanarayanan, R. ^{[2
]}

Dhalenne, G. ^{[2
]}

Revcolevschi, A. ^{[2
]}

Sood, A. K. ^{[1
]}

机构：

[1] Indian Inst Sci, Dept Phys, Bangalore 560012, Karnataka, India

[2] Univ Paris 11, CNRS, UMR8648, ICMMO,Lab Physicochim Etat Solide, F-91405 Orsay, France

[3] Ecole Cent Paris, CNRS, UMR8580, Lab Struct Proprietes & Modelisat Solides, F-92295 Chatenay Malabry, France

[4] Tata Inst Fundamental Res, Bombay 400005, Maharashtra, India

来源：

PHYSICAL REVIEW B | 2008年 / 78卷 / 21期

关键词：

crystal structure; dysprosium compounds; lutetium compounds; phonon spectra; phonon-phonon interactions; Raman spectra; solid-state phase transformations; specific heat; X-ray diffraction;

D O I：

10.1103/PhysRevB.78.214102

中图分类号：

T [工业技术];

学科分类号：

08 ;

摘要：

We present here temperature-dependent Raman, x-ray diffraction, and specific heat studies between room temperature and 12 K on single crystals of spin-ice pyrochlore compound Dy2Ti2O7 and its nonmagnetic analog Lu2Ti2O7. Raman data show a "new" band not predicted by factor group analysis of Raman-active modes for the pyrochlore structure in Dy2Ti2O7, appearing below a temperature of T-c=110 K with a concomitant contraction of the cubic unit cell volume as determined from the powder x-ray diffraction analysis. Low-temperature Raman experiments on O-18-isotope substituted Dy2Ti2O7 confirm the phonon origin of the new mode. These findings, absent in Lu2Ti2O7, suggest that the room-temperature cubic lattice of the pyrochlore Dy2Ti2O7 undergoes a "subtle" structural transformation near T-c. We find anomalous redshift of some of the phonon modes in both the Dy2Ti2O7 and the Lu2Ti2O7 as the temperature decreases, which is attributed to strong phonon-phonon anharmonic interactions.

引用

页数：10

共 47 条

[1] QUADRUPOLE INTERACTIONS AND RELAXATION EFFECTS IN DY2TI2O7 [J].