arXiv subjects

Kristin Kliemt

Publications and source records attributed to Kristin Kliemt.

44 records · Page 3Linked to original sources

arXiv2018

Magnetic anisotropy in HoIr$_2$Si$_2$ ($I4/mmm$)

Single crystals of HoIr$_2$Si$_2$ with the body-centered ThCr$_2$Si$_2$-type structure ($I4/mmm$) were grown by Bridgman method from indium flux. Single crystal structure determination yielded a Si-z position of 0.378(1) in the structure. We excluded the presence of the high temperature phase with the primitive CaBe$_2$Ge$_2$-type structure ($P 4/n m m$) by powder X-ray diffraction. Magnetic measurements on the single crystals yield a Neel temperature of $T_{\rm N}=22\,\rm K$. In the inverse magnetic susceptibility a strong anisotropy with Weiss temperatures $Θ_{W}^{001}=26\,\rm K$ and $Θ_{W}^{100}=-26\,\rm K$ occurs above $T_{\rm N}$. The effective magnetic moment $μ_{\rm eff}^{001}=10.64μ_{B}$ and $μ_{\rm eff}^{100}=10.53μ_{B}$ is close to the expected value for a free Ho$^{3+}$ ion, $μ_{\rm eff}^{calc}=10.6μ_{B}$. The field dependent magnetization shows a step-like behaviour due to crystalline electric field effects.

cond-mat.str-el↗

arXiv2017

Angle-dependent electron spin resonance of YbRh$_2$Si$_2$ measured with planar microwave resonators and in-situ rotation

We present a new experimental approach to investigate the magnetic properties of the anisotropic heavy-fermion system YbRh$_2$Si$_2$ as a function of crystallographic orientation. Angle-dependent electron spin resonance (ESR) measurements are performed at a low temperature of 1.6 K and at an ESR frequency of 4.4 GHz utilizing a superconducting planar microwave resonator in a $^4$He-cryostat in combination with in-situ sample rotation. The obtained ESR g-factor of YbRh$_2$Si$_2$ as a function of the crystallographic angle is consistent with results of previous measurements using conventional ESR spectrometers at higher frequencies and fields. Perspectives to implement this experimental approach into a dilution refrigerator and to reach the magnetically ordered phase of YbRh$_2$Si$_2$ are discussed.

cond-mat.str-el↗

arXiv2017

Strong magnetic frustration in Y$_{3}$Cu$_{9}$(OH)$_{19}$Cl$_{8}$: a distorted kagome antiferromagnet

We present the crystal structure and magnetic properties of Y$_{3}$Cu$_{9}$(OH)$_{19}$Cl$_{8}$, a stoichiometric frustrated quantum spin system with slightly distorted kagome layers. Single crystals of Y$_{3}$Cu$_{9}$(OH)$_{19}$Cl$_{8}$ were grown under hydrothermal conditions. The structure was determined from single crystal X-ray diffraction and confirmed by neutron powder diffraction. The observed structure reveals two different Cu-positions leading to a slightly distored kagome layer in contrast to the closely related YCu$_{3}$(OH)$_{6}$Cl$_{3}$. Curie-Weiss behavior at high-temperatures with a Weiss-temperature $θ_{W}$ of the order of $-100$ K, shows a large dominant antiferromagnetic coupling within the kagome planes. Specific-heat and magnetization measurements on single crystals reveal an antiferromagnetic transition at T$_{N}=2.2$ K indicating a pronounced frustration parameter of $θ_{W}/T_{N}\approx50$. Optical transmission experiments on powder samples and single crystals confirm the structural findings. Specific-heat measurements on YCu$_{3}$(OH)$_{6}$Cl$_{3}$ down to 0.4 K confirm the proposed quantum spin-liquid state of that system. Therefore, the two Y-Cu-OH-Cl compounds present a unique setting to investigate closely related structures with a spin-liquid state and a strongly frustrated AFM ordered state, by slightly releasing the frustration in a kagome lattice.

cond-mat.str-el↗

arXiv2016

Single crystal growth and characterization of GdRh$_2$Si$_2$

High-temperature indium flux growth was applied to prepare single crystals of GdRh$_2$Si$_2$ by a modified Bridgman method leading to mm-sized single crystals with a platelet habitus. Specific heat and susceptibility data of GdRh$_2$Si$_2$ exhibit a pronounced anomaly at $T_N = 107\rm \,K$, where the AFM ordering sets in. Magnetic measurements on the single crystals were performed down to $T = 2$\,K in external fields from B = 0 - 9\,T applied along the $[100]$-, $[110]$- and $[001]$-direction of the tetragonal lattice. The effective magnetic moment determined from a Curie-Weiss fit agrees well with values from literature, and is larger than the theoretically predicted value. Electrical transport data recorded for current flow parallel and perpendicular to the $[001]$-direction show a large anisotropy below $T_N$. The residual resistivity ratio $\rm RRR=ρ_{300K}/ρ_{0}\sim 23$ demonstrates that we succeeded in preparing high-quality crystals using high-temperature indium flux-growth.

cond-mat.str-el↗

arXiv2016

Characterization of YbNi$_4$(P$_{1-{\it x}}$As$_{\it x}$)$_2$, $x = 0, 0.2$ single crystals grown by Czochralski method

We have investigated large single crystals of YbNi$_4$P$_2$ that were grown from a levitating melt by the Czochralski method. The new samples facilitate the determination of the absolute values of the electrical resistivity. Phase pure polycrystalline samples of the non-magnetic reference LuNi$_4$P$_2$ were prepared and the electrical resistivity was measured. Furthermore we have grown a single crystal of the As substituted compound YbNi$_4$(P$_{1-{\it x}}$As$_{\it x}$)$_2$, $x = 0.2$ and investigated the homogenity of the As distribution.

cond-mat.str-el↗

arXiv2016

Crystal growth by Bridgman and Czochralski method of the ferromagnetic quantum critical material YbNi$_4$P$_2$

The tetragonal YbNi$_4$P$_2$ is one of the rare examples of compounds that allow the investigation of a ferromagnetic quantum critical point. We report in detail on two different methods which have been used to grow YbNi$_4$P$_2$ single crystals from a self-flux. The first, a modified Bridgman method, using a closed crucible system yields needle-shaped single crystals oriented along the $[001]$-direction. The second method, the Czochralski growth from a levitating melt, yields large single crystals which can be cut in any desired orientation. With this crucible-free method, samples without flux inclusions and a resistivity ratio at 1.8 K of RR$_{1.8\rm K}= 17$ have been grown.

cond-mat.str-el↗

arXiv2016

Avoided ferromagnetic quantum critical point: Antiferromagnetic ground state in substituted CeFePO

We have investigated single crystals of two substitution series Ce(Ru$_{1-x}$Fe$_{x}$)PO and CeFe(As$_{1-y}$P$_{y}$)O in the vicinity to the quantum critical material CeFePO by means of magnetic-susceptibility and specific-heat measurements. We observe an antiferromagnetic ground state in the vicinity of the quantum critical point, with pronounced metamagnetic transitions for $H\parallel c$, which is the magnetically hard direction. Our results verify that a ferromagnetic quantum critical point is avoided in substituted CeFePO, because we clearly demonstrate that the ferromagnetic ground state changes into an antiferromagnetic one, when approaching the quantum critical point.

cond-mat.str-el↗

arXiv2016

Signatures of phase transitions in the microwave response of YbRh2Si2

We used a spectroscopic microwave technique utilizing superconducting stripline resonators at frequencies between 3 GHz and 15 GHz to examine the charge dynamics of YbRh2Si2 at temperatures and magnetic fields close to the quantum critical point. The different electronic phases of this heavy-fermion compound, in particular the antiferromagnetic, Fermi-liquid, and non-Fermi-liquid regimes, were probed with temperature-dependent microwave measurements between 40 mK and 600 mK at a set of different magnetic fields up to 140 mT. Signatures of phase transitions were observed, which give information about the dynamic response of this peculiar material that exhibits field-tuned quantum criticality and pronounced deviations from Fermi-liquid theory.

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