Probing phonons

Probing spin correlations with phonons in the strongly frustrated magnet ZnCr2O4.

The spin-lattice coupling plays an important role in strongly frustrated magnets. In ZnCr2O4, an excellent realization of the Heisenberg antiferromagnet on the pyrochlore network, a lattice distortion relieves the geometrical frustration through a spin-Peierls-like phase transition at T(c)=12.5 K. Conversely, spin correlations strongly influence the elastic properties of a frustrated magnet. By...

Probing two-subband systems in a quantizing magnetic field with non-equilibrium phonons

We propose to use phonon absorption spectroscopy to study many-body gaps and phases of two-subband heterostructures in the quantum Hall regime. Implications of the spinorbit interaction for phonon absorption in this system are considered. Phonon spectroscopy is a powerful experimental technique that has been successfully used in the study of the properties of a two-dimensional (2D) electron gas...

Observation of chiral phonons.

Chirality reveals symmetry breaking of the fundamental interaction of elementary particles. In condensed matter, for example, the chirality of electrons governs many unconventional transport phenomena such as the quantum Hall effect. Here we show that phonons can exhibit intrinsic chirality in monolayer tungsten diselenide. The broken inversion symmetry of the lattice lifts the degeneracy of cl...

Photons refrigerating phonons

Phonons as Goldstone bosons

The implications of the hidden, spontaneously broken symmetry for the properties of the sound waves of a solid are analyzed. Although the discussion does not go beyond standard wisdom, it presents some of the known results from a different perspective. In particular, I argue that, as a consequence of the hidden symmetry, the equations of motion for a sound wave necessarily contain nonlinear ter...