Spin‐phonon coupling and two‐magnons scattering behaviors in hexagonal NiAs‐type antiferromagnetic MnTe epitaxial films

Abstract

Temperature‐dependent Raman scattering spectra of NiAs‐type MnTe epitaxial films were measured to explore the temperature evolution of phonon modes and especially the spin‐phonon coupling across Néel temperature (TN). A significant deviation from an anharmonic mode below TN strongly supports the existence of spin‐phonon interaction, and its coupling strength is calculated to be approximately −0.16 cm−1 from the E2g phonon. Two‐magnons (2M) scattering is found, which is proposed to closely relate to the nearest neighbor (NN) exchange interaction. These data elucidate the nature of the spin‐phonon coupling in antiferromagnetic (AFM) MnTe and can avail to develop MnTe‐based AFM spintronic devices.

Femtosecond phononic coupling to both spins and charges in a room temperature antiferromagnetic semiconductor

“…Interestingly, in a spectral range centred at 1.71 eV, which corresponds to the rising edge of the band-gap [22,23], pronounced oscillations at the frequency of 5.3 THz are visible. This value is consistent with the frequency of two degenerate E 2g phonon modes observed in the Raman spectrum of α-MnTe [24]. These lattice modes imply oscillations of Te atoms, as displayed in Fig.…”

“…The temperature dependence of the linewidth displays a discontinuity in correspondence of the magnetic phase transition. Both features are unique of this specific mode [24]. The measurements reported here confirm the spin-phonon coupling in the frequency domain from the spectral analysis in Fig.…”

“…In solids the frequency and lifetime of lattice vibrations may be temperature-dependent, regardless of any coupling to spins. This is indeed the case also for several phonon modes in α-MnTe , as reported by temperature-dependent Raman scattering data [24]. However, the same experiment reveals that the temperature dependence of the 5.3 THz lattice mode differs from the one of the other phonons, as the long-range antiferromagnetic order is established (i.e.…”

“…However, the same experiment reveals that the temperature dependence of the 5.3 THz lattice mode differs from the one of the other phonons, as the long-range antiferromagnetic order is established (i.e. below T N [24]). More in details, the frequency of the 5.3 THz mode increases as the temperature is lowered in a more pronounced way than in the case of the other phonons.…”

Lattice-driven femtosecond magnon dynamics in $α$-MnTe

“…This material has been experimentally proven to possess a substantial spin-lattice coupling, since both the frequency and the lifetime of two degenerate Raman-active phonon modes with 5.3 THz frequency are significantly affected by the establishment of the long-range magnetic order [20]. Hexagonal MnTe is thus a representative choice for the material class of dielectric correlated antiferromagnets.…”