arXiv subjects

Petr Král

Publications and source records attributed to Petr Král.

6 recordsLinked to original sources

arXiv2026

Lifting the degeneracy of quantum spin liquid phase by uniaxial pressure

We report muon spin relaxation/rotation ($μ$SR) measurements of the candidate three-dimensional (3D) quantum spin liquid (QSL) PbCuTe$_2$O$_6$, hosting $S=1/2$ moments, under controlled in situ [110] uniaxial compression up to $σ_{[110]}=37.7$~MPa. A small directional lattice perturbation significantly modifies the local magnetic response, while above $σ_{\rm cr}\sim10.8$\,MPa the relaxation rates are strongly enhanced and the internal-field distribution is substantially broadened. These changes occur along with the local crystalline symmetry breaking. While, no evidence for conventional static long-range magnetic order is observed, the compression drives the system towards a structurally modified and strongly correlated state in which enhanced quasi-static correlations coexist with persistent slow spin dynamics. This work demonstrates a clean and symmetry-selective route to control frustrated exchange landscape and access hidden magnetic instabilities in a 3D QSL candidate opening up the possibilities to tune other correlated systems where intrinsic coupling between magnetic and lattice degrees of freedom are relevant.

cond-mat.str-el↗

arXiv2003

Control of catalytic activity of proteins in vivo by nanotube ropes excited with infrared light

We discuss the possibility of controlling biological systems, by exciting in the near infrared region {\it hybrid} metallic nanotube ropes, dressed with proteins and embedded in the biosystems. If one nanotube, in a double-tube rope, is filled with metallofullerenes and the other is empty, the two tubes change their opposite equilibrium charging during the irradiation. The resulting change of the local electric field can deform proteins attached to the tubes, and change their catalytic properties.

physics.bio-ph↗

arXiv2002

Two-Step Enantio-selective Optical Switch

We present an optical "enantio-selective switch", that, in two steps, turns a ("racemic") mixture of left-handed and right-handed chiral molecules into the enantiomerically pure state of interest. The optical switch is composed of an "enantio-discriminator" and an "enantio-converter" acting in tandem. The method is robust, insensitive to decay processes, and does not require molecular preorientation. We demonstrate the method on the purification of a racemate of (transiently chiral) D$_2$S$_2$ molecules, performed on the nanosecond timescale.

quant-ph↗

arXiv2002

Nanoscale Processing by Adaptive Laser Pulses

We theoretically demonstrate that atomically-precise ``nanoscale processing" can be reproducibly performed by adaptive laser pulses. We present the new approach on the controlled welding of crossed carbon nanotubes, giving various metastable junctions of interest. Adaptive laser pulses could be also used in preparation of other hybrid nanostructures.

cond-mat.mtrl-sci↗

arXiv2002

Laser Spinning of Nanotubes: A path to fast-rotating microdevices

We show that circularly polarized light can spin nanotubes with GHz frequencies. In this method, angular moments of infrared photons are resonantly transferred to nanotube phonons and passed to the tube body by "umklapp" scattering. We investigate experimental realization of this ultrafast rotation in carbon nanotubes, levitating in an optical trap and undergoing mechanical vibrations, and discuss possible applications to rotating microdevices.

physics.atm-clus↗

arXiv1996

Generalized gradient expansions in quantum transport equations

Gradient expansions in quantum transport equations of a Kadanoff-Baym form have been reexamined. We have realized that in a consistent approach the expansion should be performed also inside of the self-energy in the scattering integrals of these equations. In the first perturbation order this internal expansion gives new correction terms to the generalized Boltzman equation. These correction terms are found here for several typical systems. Possible corrections to the theory of a linear response to weak electric fields are also discussed.

cond-mat.stat-mech↗