arXiv subjects

Tilen Knaflič

Publications and source records attributed to Tilen Knaflič.

3 recordsLinked to original sources

arXiv2026

Intrinsic single crystals of MnTe altermagnet

We report the synthesis methodology, structure, and intrinsic properties of ultra-high quality single crystals of MnTe, an archetypal altermagnet. The crystals, obtained from self-flux method, are nearly free from crystal imperfections and disproportionate chemical compositions as seen by various investigation methods. In measurements under quasi free-standing configuration minimizing stress induced effects, the crystals exhibit complex and anisotropic domain kinetics in both superheating and supercooling regimes around the altermagnetic transition at $T_{\mathrm{N}} = 310\,\mathrm{K}$. An Anderson insulating state is observed below $T_{\mathrm{MI}}\approx 150\,\mathrm{K}$ with a carrier density of about $1.6\times 10^{17}\,\mathrm{cm}^{-3}$, being sharply contrast to metallic states usually seen in Te-deficit samples. Nevertheless, hallmarks of altermagnetism, anomalous Hall effect and X-ray magnetic circular dichroism signal, are robust in this intrinsic limit, however with significantly reduced magnitudes.

cond-mat.str-el↗

arXiv2025

Influence of La-doping on the magnetic properties of the two-dimensional spin-gapped system SrCu$_2$(BO$_3$)$_2$

Aliovalent doping of the two-dimensional dimer antiferromagnet SrCu$_2$(BO$_3$)$_2$ has long been proposed as a potential route toward realizing resonating valence bond (RVB) superconductivity in this system; however, experimental progress has remained limited. This study explores the effects of La doping on the ground state of SrCu$_2$(BO$_3$)$_2$ and reports the first flux growth of Sr$_{1-x}$La$_x$Cu$_2$(BO$_3$)$_2$ single crystals with nominal doping levels up to $x$ = 0.15. Powder X-ray diffraction and energy-dispersive X-ray spectroscopy confirm the successful incorporation of La on the Sr sites within the tetragonal $I\bar{4}2m$ structure, although the effective doping was limited to approximately 50% of the nominal concentration. La doping induces systematic changes in the magnetic properties, with a reduction of the effective spin gap $Δ$ from ~28.2K to ~20.3 K at $x$ = 0.15, as determined from low-temperature magnetic susceptibility. X-band electron spin resonance measurements reveal the emergence of unpaired Cu$^{2+}$ spins in La-doped SrCu$_2$(BO$_3$)$_2$ single crystals, which develop antiferromagnetic correlations below ~5.5 K. These findings corroborate the breaking of the local spin dimers induced by La doping. Despite this, no superconductivity is observed across the entire doping range studied. The present study demonstrates that at low doping levels, electron doping locally destabilizes the spin-singlet ground state in SrCu$_2$(BO$_3$)$_2$, while the intrinsic spin dynamics of the dimer lattice remain largely preserved.

cond-mat.str-el↗

arXiv2024

Higher-magnesium-doping effects on the singlet ground state of the Shastry-Sutherland SrCu2(BO3)2

Doping of quantum antiferromagnets is an established approach to investigate the robustness of their ground state against the competing phases. Predictions of doping effects on the ground state of the Shastry-Sutherland dimer model are here verified experimentally on Mg-doped SrCu2(BO3)2. A partial incorporation of Mg2+ on the Cu2+-site in the SrCu2(BO3)2 structure leads to a subtle but systematic lattice expansion with the increasing Mg-doping concentration, which is accompanied by a concomitant decrease in the spin gap, the Curie-Weiss temperature and the peak temperature of the susceptibility. These findings indicate a doping-induced breaking of Cu2+ spin-1/2 dimers which is also corroborated by X-band EPR spectroscopy that points to a systematic increase in intensity of free Cu2+ sites with increasing Mg-doping concentration. Extending the Mg-doping up to nominal x = 0.10 or SrCu1.9Mg0.1(BO3)2, in the magnetisation measurements taken up to 35 T, a suppression of the pseudo-1/8 plateau is found along with a clear presence of an anomaly at an onset critical field H'C0 ~ 9 T. The latter, absent in pure SrCu2(BO3)2, emerges due to the coupling of liberated Cu2+ spin-1/2 entities in the vicinity of Mg-doping induced impurities.

cond-mat.str-el↗