Hybrid quasiparticles within the orthorhombic or hexagonal topology of RMO3 (R=Nd,Pr,Tm,Er; M=Mn,Cr) under strong magnetic fields

R. SOPRACASE; K. HOLLDACK; L. DEL CAMPO; N. E. MASSA ; M.J. MARTINEZ-LOPE; J.A. ALONSO

Denver, CO, USA

Congreso; American Physical Soceity March Meeting; 2014

American Physical Society

We report on magnetoelectric quasiparticles that originate from electronic Coulomb and exchange correlations using a Bruker IFS125-HR interferometer at 0.5 cm−1 resolution in the THz beamline of the electron storage ring BESSYII in Berlin. Orthorhombic NdMnO3 and hexagonal TmMnO3 have quasiparticles at energies of zone center magnons. In both cases, increasing the applied field, the ∼ 20 cm−1 line matching the lowest energy magnon, has its intensity reduced sharply while bands associated in TmMnO3 to magnon--acoustical phonon dispersion crossing and gap opening behave differently. The line at ∼ 48 cm−1, the higher branch of the phonon gap, shows a Zeeman splitting-like behavior, while the lower branch at ∼ 31 cm−1 has weak field dependences. The asymmetric envelope peaking at ∼35 cm−1 in NdMnO3 weakens, softens, and evolves at 8 T into two unresolved bands suggesting field induced TA+magnon coupling materializing a condition for a multiferroic state. Metastable orthorhombic ErMnO3 has two bands at 5 K which resembles those of NdMnO3. A remarkable 35 cm−1 Zeeman splitting at 5 K in PrCrO3 is tentatively associated to Cr3+ electrons in a distorted polarizable p-d bond. ErCrO3 shows such a feature at 50 cm−1 as well additional zero field splitting at 8 and 9 cm−1 in the spin reorientation phase.