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The magnetic response at the metalinsulator transition in La1 xSrxTiO3 (abstract)

Summary: The magnetic response at the metal­insulator transition
in La1 xSrxTiO3 (abstract)
R. Osborna)
Materials Science Division, Argonne National Laboratory, Argonne, Illinois 60439-4845
M. C. Aronson
Department of Physics, University of Michigan, Ann Arbor, Michigan 48109-1120
E. A. Goremychkin
Frank Laboratory of Neutron Physics, JINR, 141980 Dubna, Moscow Region, Russia
J. E. Greedan
Institute for Materials Research, McMaster University, Hamilton, Ontario, Canada L8S 4M1
We report on recent inelastic neutron scattering measurements of the magnetic response close to the
metal­insulator transition in La1 xSrxTiO3 . Specific heat and susceptibility data from Tokura et al.1
give evidence for a divergent effective mass at the critical concentration xc 0.05 in agreement with
recent mean-field theories of the transition. The mass enhancement is believed to arise from the
formation of a d-electron resonance at the Fermi energy close to the transition. The aim of this
investigation is to look for evidence of this resonance in the dynamic magnetic susceptibility. We
studied samples with x 0, 0.05, and 0.2 using incident energies between 25 and 200 meV. After
correction for the phonon scattering, we observe a broad response above a threshold of 20­30 meV
extending to over 100 meV. In addition, the Mott insulating antiferromagnet (x 0) has a peak at
40 meV, consistent with the estimated activation energy derived from resistivity measurements. This


Source: Aronson, Meigan - Department of Physics and Astronomy, SUNY at Stony Brook


Collections: Materials Science; Physics