arXiv subjects

R. Tesař

Publications and source records attributed to R. Tesař.

3 recordsLinked to original sources

arXiv2025

Antiferromagnetic resonance in $α$-MnTe

Antiferromagnetic resonance in a bulk $α$-MnTe crystal is investigated using both frequency-domain and time-domain THz spectroscopy techniques. At low temperatures, an excitation at the photon energy of $(3.5\pm 0.1)$~meV is observed and identified as a magnon mode through its distinctive dependence on temperature and magnetic field. This behavior is reproduced using a simplified model for antiferromagnetic resonance in an easy-plane antiferromagnet. The results of our experiments, when compared to exchange constants established in the literature, allow us to extract the out-of-plane component of the single-ion magnetic anisotropy reaching $(40\pm10)$~$μ$eV.

cond-mat.mtrl-sci↗

arXiv2015

Anisotropic behaviour of transmission through thin superconducting NbN film in parallel magnetic field

Transmission of terahertz waves through a thin layer of the superconductor NbN deposited on an anisotropic R-cut sapphire substrate is studied as a function of temperature in a magnetic field oriented parallel with the sample. A significant difference is found between transmitted intensities of beams linearly polarized parallel with and perpendicular to the direction of applied magnetic field.

cond-mat.supr-con↗

arXiv2013

Far-infrared electrodynamics of thin superconducting NbN film in magnetic field

We studied a thin superconducting NbN film in magnetic fields up to 8 T above the zero- temperature limit by means of time-domain terahertz and scanning tunneling spectroscopies in order to understand the vortex response. Scanning tunneling spectroscopy was used to determine the optical gap and the upper critical field of the sample. The obtained values were subsequently used to fit the terahertz complex conductivity spectra in the magnetic field in the Faraday geometry above the zero temperature limit. These spectra are best described in terms of the Coffey-Clem self-consistent solution of a modified London equation in the flux creep regime.

cond-mat.supr-con↗