Bulletin of the American Physical Society
APS March Meeting 2013
Volume 58, Number 1
Monday–Friday, March 18–22, 2013; Baltimore, Maryland
Session J19: Quantum Criticality in Lanthanide/Actinide & Related Systems - Experiment |
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Sponsoring Units: DCMP Chair: Makariy Tanatar, Ames Laboratory Room: 321 |
Tuesday, March 19, 2013 2:30PM - 2:42PM |
J19.00001: Quantum criticality of YbBiPt G.M. Schmiedeshoff, E.D. Mun, S.L. Bud'ko, C. Martin, H. Kim, M.A. Tanatar, R. Prozorov, J.-H. Park, T. Murphy, N. Dilley, P.C. Canfield YbBiPt is a stoichiometric heavy fermion compound with an enormous Sommerfeld coefficient and a magnetic ground state that can be suppressed by fields of about 4 kOe. We will present and discuss recent thermodynamic and transport measurements, and the evidence for field induced quantum criticality in this material. Work at Ames Laboratory was supported by the Department of Energy, Basic Energy Sciences under Contract No. DE-AC02-07CH11358. The National High Magnetic Field Laboratory was supported by the US National Science Foundation, the State of Florida and the US Department of Energy. Work at Occidental College was supported by the National Science Foundation under DMR-1006118. [Preview Abstract] |
Tuesday, March 19, 2013 2:42PM - 2:54PM |
J19.00002: ABSTRACT WITHDRAWN |
Tuesday, March 19, 2013 2:54PM - 3:06PM |
J19.00003: The High-Field Fermi Surface of YbRh$_2$Si$_2$ Aaron Sutton, Patrick M.C. Rourke, Valentin Taufour, Alix McCollam, Gerard Lapertot, Georg Knebel, Jacques Flouquet, Stephen R. Julian We report the culmination of our de Haas-van Alphen (dHvA) oscillation rotation studies on the heavy Fermion material YbRh$_2$Si$_2$. Past measurements included rotations in the a-b and a-c planes and resulted in the observation of a previously unobserved frequency attributed to the so-called J-sheet of the Fermi surface. While the purpose of these measurements was to determine whether or not the high field Fermi surface resembled a small or large Fermi surface, the measurements have highlighted the need for more advanced band structure calculations in order to determine its nature. In our latest measurements we completed our study by rotating from the (110) direction towards the c-axis. The experiment was successful in elucidating a new aspect of the Fermi surface, and though qualitative agreement with rudimentary band structure calculations was observed, the measurement has reinforced the need for a more comprehensive theoretical understanding of the material. [Preview Abstract] |
Tuesday, March 19, 2013 3:06PM - 3:18PM |
J19.00004: CePt$_2$In$_7$: Focused Ion Beam Sample Preparation for Quantum Oscillation Measurements under High Pressure Jakob Kanter, P. Moll, S. Friedemann, P. Alireza, M. Sutherland, S. Goh, F. Ronning, E.D. Bauer, B. Batlogg Electronic transport measurements under high pressures face several experimental challenges due to confined sample space and high forces acting on contacts and leads. As a result conventional preparation methods are often limited in the number of possible leads and usually do not allow for sample structuring. The Focused Ion Beam (FIB) enables sample contacting and structuring down to a sub-micrometre scale, making the measurement of several samples with complex shapes on a single anvil feasible. This talk will discuss Shubnikov-de Haas measurements of FIB prepared CePt$_2$In$_7$ samples under high pressures. CePt$_2$In$_7$ belongs to the Ce$_m$\emph{M}$_n$In$_{3m+2n}$ heavy fermion family. Compared to the Ce\emph{M}In$_5$ members of this group, the structure of CePt$_2$In$_7$ has a more pronounced two dimensional character, but also exhibits an antiferromagnetically ordered as well as a superconducting phase. We have studied the changes of the quasiparticle masses for the various orbits as function of pressure approaching the quantum critical point. [Preview Abstract] |
Tuesday, March 19, 2013 3:18PM - 3:30PM |
J19.00005: A THz spectroscopy study of the field-induced quantum phase transition in the heavy fermion antiferromagnet CeCu$_2$Ge$_2$ Grace Bosse, C.M. Morris, Y. Li, J. Eckstein, N.P. Armitage We report time domain THz spectroscopy data of a thin film of the heavy fermion compound CeCu$_2$Ge$_2$ in the presence of a magnetic field. It has been shown that it is possible to tune the antiferromagnetic long-range order of CeCu$_2$Ge$_2$ towards a quantum critical point using magnetic field as a tuning parameter. Measurements to obtain the frequency dependent complex conductivity as a function of temperature and field were taken down to temperatures below the onset of magnetic order and fields as high as 7 T. The effects of the quantum critical fluctuations on the frequency dependent scattering rate and mass renormalization, which are obtained using an extended Drude model analysis, will be discussed. [Preview Abstract] |
Tuesday, March 19, 2013 3:30PM - 3:42PM |
J19.00006: Quantum Criticality in high purity specimens of Ce$_{2}$Rh$_{3}$Ge$_{5}$ and Ce$_{2}$Pt$_{3}$Si$_{5}$ Eric D. Bauer, Ryan E. Baumbach, Xin Lu, Ross D. McDonald, Filip Ronning, Joe D. Thompson We report results for high purity specimens of the heavy fermion antiferromagnets Ce$_{2}$Rh$_{3}$Ge$_{5}$ and Ce$_{2}$Pt$_{3}$Si$_{5}$, which have similar ordering temperatures: T$_{N} =$ 5.5 K and 6.3 K, respectively, and belong to the same family of materials that includes the pressure-induced superconductor Ce$_{2}$Ni$_{3}$Ge$_{5}$. Our measurements show that the antiferromagnetic state is suppressed to zero temperature at similar magnetic fields (H$_{c} =$ 23 T and 36 T, respectively), suggesting comparable magnetic energy scales in these compounds. In contrast, while the pressure needed to access a quantum critical point (QCP) in Ce$_{2}$Rh$_{3}$Ge$_{5}$ is extremely low (P$_{c}$ $\sim$ 5 kbar), the N\'{e}el temperature for Ce$_{2}$Pt$_{3}$Si$_{5}$ is insensitive to pressures up to 15 kbar. This result implies that although these compounds are markedly similar, the mechanism that drives the QCP in Ce$_{2}$Rh$_{3}$Ge$_{5}$ is not present in Ce$_{2}$Pt$_{3}$Si$_{5}$. We discuss possible differences between these compounds and mechanisms for their quantum criticality with an emphasis on how the shape of the Fermi surface affects their physical properties. [Preview Abstract] |
Tuesday, March 19, 2013 3:42PM - 3:54PM |
J19.00007: Magnetic cluster glass formation in Ni-V close to the disordered ferromagnetic quantum phase transition Ruizhe Wang, Sara Ubaid-Kassis, Almut Schroeder, P.J. Baker, F.L. Pratt, S.J. Blundell, T. Lancaster, I. Franke, J.S. Moeller, Thomas Vojta The d-metal alloy Ni$_{1-x}$V$_{x}$ undergoes a quantum phase transition from a ferromagnetic ground state to a paramagnetic ground state as the vanadium concentration $x$ is increased. We present magnetization, ac-susceptibility and muon-spin relaxation data at several vanadium concentrations below and above the critical concentration $x_c \approx$ 11$\%$ where the onset of ferromagnetic order is suppressed. Below $x_c$, Ni$_{1-x}$V$_{x}$ is characterized as a strongly disordered ferromagnet since the muon data reveal a broad magnetic field distribution. Above $x_c$, the temperature dependence of the magnetic susceptibility is best described in terms of a magnetic quantum Griffiths phase. At the lowest temperatures, we identify a magnetic cluster glass phase which masks the actual ferromagnetic quantum critical point. We study how this cluster glass is formed (i) by lowering the temperature from the quantum Griffiths phase and (ii) by increasing the vanadium concentration starting from the disordered ferromagnet. The onset of the cluster glass phase is recognized by a change of the magnetic dynamics revealed through susceptibility and muon-spin relaxation measurements. [Preview Abstract] |
Tuesday, March 19, 2013 3:54PM - 4:06PM |
J19.00008: Anisotropic transport and magnetic properties, and magnetic-field tuned ground states of CeZn$_{11}$ H. Hodovanets, S.L. Bud'ko, M.G. Kim, D.K. Pratt, A. Kreyssig, A.I. Goldman, P.C. Canfield We have studied the electrical, magnetic, and thermal properties of single crystals of CeZn$_{11}$ by the means of magnetization, resistivity, heat capacity, and thermoelectric power. The compound exhibits an antiferromagnetic long-range order below 2.0 K. The zero-field temperature dependent resistivity of CeZn$_{11}$ is similar to that of other strongly correlated, Kondo lattice, compounds. $T_N$ is suppressed with the applied magnetic field and disappears for $H\sim$47.5 kOe ($H\|$[110]) and $H\sim$ 120 kOe ($H\|$[011]). Temperature-dependent resistivity for $H\|$[110] shows sub-linear behavior up to 2.5 K for $H$=45 kOe, followed by Fermi liquid behavior for limited range of temperatures ($T<$1.1 K) and fields (47.5 kOe$\leq H\leq$60 kOe). The $\it H-T$ phase diagrams for $H\|$[110] and $H\|$[011] will be discussed. [Preview Abstract] |
Tuesday, March 19, 2013 4:06PM - 4:18PM |
J19.00009: Electrical resistivity of CeZn$_{11}$ under pressure Valentin Taufour, Stella K. Kim, Halyna Hodovanets, Sergey L. Bud'ko, Paul C. Canfield In most Ce-based intermetallic compounds, the magnetic exchange is assumed to be due to the RKKY interaction. This interaction competes with the Kondo interaction, leading to the suppression of the magnetic order and the possibility of field and/or pressure induced quantum criticality. In order to study this competition in CeZn$_{11}$, a compound that orders antiferromagnetically below $T_N = 2$~K, we performed electrical resistivity measurements on a single crystal of CeZn$_{11}$ under pressure up to $5$~GPa in a Bridgman pressure cell modified to use a liquid pressure transmitting medium (1:1 mixture of n-pentane: iso-pentane). $T_N(p)$ slightly increases and approaches a broad maximum in the studied pressure range. At ambient pressure, the antiferromagnetic order is suppressed by a magnetic field along the [1,1,0] direction of the tetragonal crystal structure. The temperature versus magnetic field phase diagram at $5$~GPa will be compared to the one at ambient pressure. [Preview Abstract] |
Tuesday, March 19, 2013 4:18PM - 4:30PM |
J19.00010: Magnetic structure of R$_{2}$CoGa$_{8}$ (R $=$ Gd, Tb and Dy) and evolution of the magnetic structures along the series of intermetallic compounds with R $=$ Gd - Tm Carlos Giles, Jose Renato Madergan, Cris Adriano, Rafael Vescovi, Pascoal Pagliuso In this work we have determined the magnetic structure of R$_{2}$CoGa$_{8}$ (R $=$ Gd, Tb and Dy) intermetallic compounds using X-ray resonant magnetic scattering in order to study the evolution of the anisotropic magnetic properties along the series for R $=$ Gd-Tm. The three compounds have a commensurate antiferromagnetic structure with a magnetic propagation vector (1/2 1/2 1/2) with N\'{e}el temperatures of 21.0, 27.5 and 15.2 K for R $=$ Gd, Tb and Dy, respectively. The critical exponent $\beta$ obtained from the temperature dependence of the integrated intensity of the resonant magnetic peaks suggest a 3D magnetism for the three compounds. The energy line shapes at the L$_{2}$ and L$_{3}$ edges of the magnetic peaks for these compounds present a purely dipolar character as demonstrated by comparison to first principle calculations. Comparing the simulated and integrated intensities corrected for absorption, we conclude that the magnetic moment direction is in the \textit{ab}-plane for Gd$_{2}$CoGa$_{8}$ compound and parallel to the $c-$axis for the Tb$_{2}$CoGa$_{8}$ and Dy$_{2}$CoGa$_{8}$ compounds. This information is used to discuss the evolution of the magnetic structure of R$_{2}$CoGa$_{8}$ series for R $=$ Gd-Tm where both the direction of the ordered moment and the ordering temperature evolution along the series can be explained through the competition between the indirect Ruderman-Kittel- Kasuya-Yoshida exchange interaction and crystalline electric field effects. [Preview Abstract] |
Tuesday, March 19, 2013 4:30PM - 4:42PM |
J19.00011: Electronic structure and Fermi surface topology in PuIn3 and PuSn3 Cheng-Ching Wang, Matthew Jones, Jian-Xin Zhu The itinerant-to-localized crossover of the 5f electrons that occurs near plutonium in the actinide series is one of the most challenging issues in condensed matter physics, while the highest superconductivity across the whole f-electron systems emerges in PuCoGa5. These novel behaviors are indicative of strong electronic correlations effects. Electronic band structure calculations serve as the first step for better understanding of these correlation effects. The compounds PuIn3 and PuSn3 crystallize into cubic AuCu3-type structure and have an actinide-actinide distance far above the Hill limit, making the 5f-ligand hybridization the dominant mechanism for Pu 5f -electron delocalization. With their simple crystallographic structure and rich magnetic and electronic properties, these two compounds provide a particularly convenient and systematic way to study the delocalization-localization crossover of Pu 5f electrons. It is particularly encouraging that PuIn3 is the first Pu-based compound in which the de-Haas van-Alphen effect has been observed. In this talk, we present a systematic study of electronic structure calculations on PuIn3 and PuSn3 in the framework of density functional theory with the generalized gradient approximation. [Preview Abstract] |
Tuesday, March 19, 2013 4:42PM - 4:54PM |
J19.00012: Quantum Criticality in the strongly correlated 3d electron system YFe$_{2}$Al$_{10}$ Liusuo Wu, Keeseong Park, Monika Gamza, Moosung Kim, Meigan Aronson A remarkable behavior in quantum critical systems is the critical scaling near the quantum critical point (QCP), where Fermi liquid (FL) physics usually breaks down. This kind of behavior has been observed in many $f$ electron based heavy fermion (HF) systems. We have measured the magnetization and specific heat of the 3$d$-electron metal YFe$_{2}$Al$_{10}$. non-FL behavior with strong divergence in magnetic susceptibility ($\chi $ $\sim$ T$^{-\gamma }$, $\gamma =$1.4) and specific heat (C$_{M}$/T$\sim$ -log T) were observed, and this suggested YFe$_{2}$Al$_{10}$ may locate close to a ferromagnetic QCP. What attracts us most is the unusual scaling of magnetic susceptibility (d$\chi $/dT$=$B$^{-\gamma }\varphi $(T/B$^{\beta }))$ and specific heat ($\Delta $C$_{M}$/T$=\psi $(T/B$^{\beta }))$, which was observed over a range more than three decades in T/B$^{\beta }$. The overall scaling behaviors mapped well with the assumption that a FL phase was resumed as the system was tuned far from the QCP, where all the critical fluctuation was suppressed. Based on the scaling analysis, a possible form of the critical free energy will also be discussed. [Preview Abstract] |
Tuesday, March 19, 2013 4:54PM - 5:06PM |
J19.00013: Terahertz conductivity of MnSi thin films J. Steven Dodge, Laleh Mohtashemi, Amir Farahani, Eric Karhu, Theodore Monchesky We present measurements of the low-frequency optical conductivity of MnSi thin films, using time-domain terahertz spectroscopy. At low temperatures and low frequencies, we extract the DC resistivity, scattering life time and plasma frequency from a Drude fit. We obtain a value of $\omega_p\simeq1.0$ eV, which can be used to estimate the renormalization coefficient through comparison with band theory. At higher temperatures, deviations from Drude behavior are observed, suggesting a loss of quasi-particle coherence. In the region of low temperatures and high frequencies, we see evidence for a crossover to the anomalous power law dependence observed by Mena \textit{et al.}\footnotemark[1] As the temperature increases, the anomalous frequency dependence becomes more pronounced, and the plasma frequency inferred from a Drude fit decreases dramatically. Above T$\approx 50$ K, $\sigma_2(\omega)$ develops a negative slope that is inconsistent with both a Drude model and the anomalous power law observed earlier,\footnotemark[1] indicating a sharp pseudogap in the conductivity spectrum. \footnotetext[1]{F.P. Mena \textit{et al.} \textrm{Phys. Rev. B.} \textrm{\bf67}, 241101(R) (2003).} [Preview Abstract] |
Tuesday, March 19, 2013 5:06PM - 5:18PM |
J19.00014: Effect of Nd Substitution on PrOs$_4$Sb$_{12}$ Investigated by $\mu$SR Experiments P.-C. Ho, B. Somsanuk, D. E. MacLaughlin, M. B. Maple, L. Shu, O. O. Bernal, T. Yanagisawa The pseudo ternary system Pr$_{1-x}$Nd$_x$Os$_4$Sb$_{12}$ has been used as a model system to investigate the effect of ferromagnetism (FM) on the unconventional superconductivity (SC) and quantum critical behavior of PrOs$_4$Sb$_{12}$ [1]. SC in this system disappears near a critical concentration $x_{cr,1}\sim 0.58$ and FM appears above $x_{cr,2}\sim 0.33$ [1,2]. The new $\mu$SR measurements have been performed on samples with $x =$ 0.25, 0.75, and 1. For $x = 1$ and 0.75, the estimated frozen moments agree with the Nd$^{3+}$ CEF ground state moment. For $x = 0.25$, neither time reversal symmetry breaking nor evidence of freezing of Nd$^{3+}$ spins was observed in zero-field $\mu$SR measurements, the behavior of which is very different than what is observed for $x = 0.45-0.55$ [2]. In the SC state, an unexpected linear $T$ dependence of the Gaussian relaxation rate was also found in the transverse field $\mu$SR data for $x = 0.25$, which is different than the plateau in PrOs$_4$Sb$_{12}$ below 1.3K [3]. [1] Ho, et al., PRB 83, 024511 (2011).[2] Ho, et al., 2010 APS March Meeting, A38.00005 (2010). [3] MacLaughlin et al., PRL 105, 019701 (2010). [Preview Abstract] |
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