arXiv subjects

I. Čurlik

Publications and source records attributed to I. Čurlik.

3 recordsLinked to original sources

arXiv2025

I. Magnetic, thermal and transport properties of YbCu$_{5-x}$Zn$_x$ alloys

Within the family of cubic YbCu$_4$X compounds ($X$ = Ni, Au and Zn), we have investigated the YbCu$_{5-x}$Zn$_x$ ($1\geq x \geq 0.7$) alloys by means of structural, magnetic, thermal and transport measurements. In the $τ1-$ YbCu$_{5-x}$Zn$_x$ (cubic AuBe$_5$ type, $0.7 \leq x \leq 1.5$) structural phase, Yb ion is in its Yb$^{3+}$ magnetic configuration. However, by increasing Zn content the unit cell grows faster than a reference computed as a Cu by Zn atoms substitution, which indicates a shift of Yb ions towards the larger Yb$^{2+}$ configuration. The magnetic behavior confirms such tendency with a clear decrease of the saturation magnetization and effective moment between $x=0.7$ and $x=1$. The specific heat at low temperature shows a logarithmic dependence characteristic for a non-fermi-liquid behavior. The characteristic energies of all studied parameters, including magneto resistivity, show notably low values as an indication that these alloys are close to a quantum critical point, which is approached from the non-magnetic side as the Zn content decreases.

cond-mat.str-el↗

arXiv2022

Evidences for magnetic dimers and skyrmion lattice formation in Eu$_2$Pd$_2$Sn

Magnetic, thermal and transport properties of the non-centrosymmetric compound Eu$_2$Pd$_2$Sn are revisited after including new measurements. In its paramagnetic phase, the outstanding feature of this compound is the formation of Eu$^{2+}$ dimers that allows to understand the deviation of the magnetic susceptibility $χ(T)$ from the C-W law below about 70\,K, the field dependent magnetization $M(B)$ variation below $\approx 80$\,K and the reduced entropy at the ordering temperature $S(T_N)= 0.64R\ln(8)$. A significant change of the exchange interactions occurs between $T\approx 70$\,K (where $θ_P = 18$\,K) and $T_N = 13.3$\,K (where $θ_P =-4.5$\,K). The strong electronic overlap, arising from the reduced Eu-Eu spacing compared with that of pure Eu$^{2+}$ is expected to power these quasiparticles formation, inducing a significant reformulation of the magnetic structure. A rich magnetic phase diagram is obtained from the analysis of the derivatives of the magnetic parameters: $\partial χ/\partial T$ and $\partial M/\partial B$, and the field dependence of the specific heat. Two critical points are recognized and a tentative description of the magnetic structures is proposed. The possible formation of a skyrmion lattice, that arises from the presence of magnetically frustrated pockets in the phase diagram, is suggested by theoretical studies on hexagonal structures exhibiting similar interactions pattern.

cond-mat.str-el↗

arXiv2014

Searching for a quantum critical point in YbCu5-xAux

Structural, magnetic, transport and thermal properties of YbCu5-xAux alloys with Au concentration between the limit of structural stability of AuBe5 type at x = 0.4 up to x = 0.7 are reported. The outstanding features of this system are: i) the constant and record high values of Cm /T 7J/molK^2 below a characteristic temperature T*, ranging between 150 mK and 350 mK. ii) A power law thermal dependence dependence Cm/T(T>T*)=A/T^q, with q = 1.3 +/- 0.1, and iii) an arising incoherent electronic scattering observed in the resistivity at T < 1K for x < 0.6 despite the fact that Yb magnetic atoms are placed in a lattice. Magnetic frustration, originated in the tetrahedral distribution of Yb atoms, appears as the responsible of the exotic behavior of this system.

cond-mat.str-el↗