Nature of the ferromagnetic-antiferromagnetic transition in Y1-xLaxTiO3

• Published in: Physical review. B 2021-07, Vol.104 (2)
• Main Authors: Hameed, S., El-Khatib, S., Olson, K. P., Yu, B., Williams, T. J., Hong, T., Sheng, Q., Yamakawa, K., Zang, J., Uemura, Y. J., Zhao, G. Q., Jin, C. Q., Fu, L., Gu, Y., Ning, F., Cai, Y., Kojima, K. M., Freeland, J. W., Matsuda, M., Leighton, C., Greven, M.
• Format: Article
• Language: English
• Subjects: antiferromagnetism; CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND SUPERFLUIDITY; ferromagnetism; magnetic phase transitions; magnetism; Mott insulators; muon spin resonance; neutron diffraction; phase transitions; small angle neutron scattering; x-ray magnetic circular dichroism
• ISSN: 2469-9950; 2469-9969

In this work, we explore the magnetically ordered ground state of the isovalently substituted Mott insulator Y1-xLaxTiO3 for x≤ 0.3 via single-crystal growth, magnetometry, neutron diffraction, x-ray magnetic circular dichroism, muon spin rotation, and small-angle neutron scattering (SANS). We find that the decrease in the magnetic transition temperature on approaching the ferromagnetic-antiferromagnetic phase boundary at the La concentration xc ≈ 0.3 is accompanied by a strong suppression of both bulk and local ordered magnetic moments, along with a volume wise separation into magnetically ordered and paramagnetic regions. The thermal phase transition does not show conventional second-order behavior since neither a clear signature of dynamic critical behavior nor a power-law divergence of the magnetic correlation length is found for the studied substitution range; this finding becomes increasingly obvious with increasing La substitution. We find no evidence for a spin-glass phase. Finally, from SANS and magnetometry measurements, we discern a crossover from easy-axis to easy-plane magnetocrystalline anisotropy with increasing La substitution. These results indicate complex changes in magnetic structure upon approaching the phase boundary.