Bulletin of the American Physical Society
APS March Meeting 2011
Volume 56, Number 1
Monday–Friday, March 21–25, 2011; Dallas, Texas
Session B22: Correlated Electrons Including "115" Materials |
Hide Abstracts |
Sponsoring Units: DCMP Chair: Johnpierre Paglione, University of Maryland Room: D163 |
Monday, March 21, 2011 11:15AM - 11:27AM |
B22.00001: Quantum critical point in UCo$_{1-x}$Fe$_{x}$Ge Noravee Kanchanavatee, Kevin Huang, James Hamlin, Ryan Baumbach, Diego Zocco, M. Brian Maple We have carried out a comprehensive study of the UCo$_{1-x}$Fe$_{x}$Ge series across the entire range of compositions 0 $\le $ x $\le $ 1, and report the results of x-ray diffraction, magnetization, specific heat, and electrical resistivity measurements to uncover the magnetic and superconducting phase diagram. Substitution of Fe into UCoGe initially results in an increase in the Curie temperature and a rapid destruction of the superconducting state. Near x = 0.2, the ferromagnetic transition is suppressed to zero temperature at an apparent quantum critical point, and the temperature dependences of the electrical resistivity and specific heat suggest non-Fermi liquid behavior. [Preview Abstract] |
Monday, March 21, 2011 11:27AM - 11:39AM |
B22.00002: Non Fermi liquid properties of Ni-V close to the ferromagnetic quantum critical point Almut Schroeder, Sara Ubaid-Kassis, Brendan Wyatt, Thomas Vojta Resistivity ($\rho )$ and magnetization ($M)$ data of the d-metal alloy Ni$_{1-x}$V$_{x}$ are presented in the vicinity of the critical vanadium concentration $x_{c}\approx $11{\%} where the onset of long-range ferromagnetic (FM) order is suppressed to zero temperature. Above x$_{c}$ the temperature ($T)$ dependence of the magnetic susceptibility is best described by simple nonuniversal power laws (e.g. \textit{M/H(T,H$\to $0) $\sim $T}$^{\alpha -1}$ ). Also the resistivity displays power laws (\textit{$\Delta \rho \sim $T}$^{n})$. Both exponents $\alpha $(x) and n(x) vary with x displaying signatures of a disordered quantum phase transition in a metal very different than of a clean 3D FM. [Preview Abstract] |
Monday, March 21, 2011 11:39AM - 11:51AM |
B22.00003: Non-Fermi Liquid behavior in Itinerant Ferromagnet, HfMnGa$_2$ Carlos Marques, Yuri Janssen, Moo Sung Kim, Liusuo Wu, Meigan Aronson Single crystals of HfMnGa$_2$, space group Pnma, were grown using a Ga self flux technique. A sharp peak in the AC susceptibility $\chi_{AC}$ shows a phase transition at $T_C\approx26 K$, followed by Curie-Weiss behavior at higher temperatures. Arrott plot analysis confirms this transition is ferromagnetic with a spontaneous moment of $\mu_0\cong0.3 \mu_B/ $Mn. HfMnGa$_2$ has a coercive field of $\sim$ 0.1 T as well as a large magnetic anisotropy that restricts the moments to point in the [010] direction. Both a large Rhodes-Wohlfarth parameter $\mu_{\mbox{fluct}}/\mu_0\cong3.6$ and low T$_C$ suggest HfMnGa$_2$ is comparable to other itinerant ferromagnets MnSi, ZrZn$_2$ and Ni$_3$Al. Resistivity $\rho(T)$ shows HfMnGa$_2$ to be metallic with $\rho(T)-\rho_0$ having a $T^{5/3}$ dependance in the ordered state. This non-Fermi liquid relationship was also observed in Ni$_3$Al and ZrZn$_2$ over a more limited range of temperatures. [Preview Abstract] |
Monday, March 21, 2011 11:51AM - 12:03PM |
B22.00004: Electronic, magnetic and structural properties of Cr$_{1-x}$V$_x$N Camilo Quintela, Francisco Rivadulla, Jose Rivas We report a systematic study on the electronic, magnetic and structural properties of stoichiometric and hole-doped CrN and present the magnetic and electronic phase diagram for the Cr$_{1-x}$V$_{x}$N series. Stoichiometric CrN is a narrow gap, correlation-induced, semiconductor that orders antiferromagnetically below 286 K. The changes in the chemical bond associated to the magnetic order result in a non-activated behavior of the resistivity in the antiferromagnetic state, showing some similarities with other materials proposed to be itinerant-AF, like CaCrO$_{3}$. Doping this state with holes drives the system towards itinerant electron behavior through a series of inhomogeneous magnetic/electronic states. Given the chemical and structural simplicity of this system, it could provide an interesting place to study the evolution from an antiferromagnet with a non-thermally activated charge transport to a paramagnetic metal in a non-oxide material. [Preview Abstract] |
Monday, March 21, 2011 12:03PM - 12:15PM |
B22.00005: Magnetic Correlations in Yb$_{4}$LiGe$_{4}$: A $\mu $SR and $^{7}$Li NMR Study S. Disseler, M.J. Graf, P. Carretta, S. Peter, N. Svensson, S.R. Giblin, A. Amato, C. Baines We present results from zero and longitudinal $\mu $SR and $^{7}$Li NMR together along with magnetization and dynamic susceptibility on the multivalent, intermetallic compound Yb$_{4}$LiGe$_{4}$. A magnetic transition at 1.4K in dynamic susceptibility is observed, corresponding to a rapid increase in the quasi-static relaxation component of the ZF MuSR spectra. The strong magnetic field dependence exhibited in these measurements demonstrates a non-trivial criticality, and suggests a close relation to the quantum critical phenomenon observed in other Yb and Ce based systems. Based on support from NMR spectra, we discuss the potential of competing low temperature phases, and the importance of the spin fluctuations in describing the observed phenomena. [Preview Abstract] |
Monday, March 21, 2011 12:15PM - 12:27PM |
B22.00006: Low-temperature specific heat of Nd$_{1-x}$Ca$_x$B$_6$ single crystals Jolanta Stankiewicz, Marco Evangelisti, Zachary Fisk We measured the heat capacity on random alloys of Nd$_{1-x }$Ca$_x$B$_6$ ($x < $ 0.4) in the 0.4 to 40 K temperature range. We calculated the lattice contribution to the specific heat, arising from the Debye-type phonons of the boron framework and Einstein-type oscillators of the cation sublattice. To this end, we used data obtained for the heat capacity of a LaB$_6$ single crystal which we measured in the same temperature range. Subtracting lattice and Schottky-type contributions from the measured heat capacity, we find that the electronic portion, linear in temperature, decreases sharply upon doping with Ca, most likely owed to changes in the Fermi surface. [Preview Abstract] |
Monday, March 21, 2011 12:27PM - 12:39PM |
B22.00007: High-pressure resistivity of CeCoIn$_5$ at low temperatures using four-point probe technique and finite element analysis Nathaniel Brady, Georgiy Tsoi, Tesfaye Gebre, Yogesh Vohra, David Hilton We performed high-pressure electronic characterization of the heavy fermion superconductor, CeCoIn$_5$. Using a designer diamond anvil four-point probe system, we measured the temperature-dependent resistivity up to 25 GPa and found evidence for a decrease in the effective mass at high pressures. We determined the resistivity using Van Der Pauws method and a finite element analysis approach. Room temperature resistivity with increasing pressure was also measured and a maximum in resistivity was observed near $\sim$8 GPa. These data suggest the existence of a pressure-dependent modification of the 4$f$ hybridization at the highest pressures [Preview Abstract] |
Monday, March 21, 2011 12:39PM - 12:51PM |
B22.00008: Exploring the antiferromagnetic superconducting phase in CeCoIn$_5$ Elizabeth Blackburn, Ted Forgan, Pinaki Das, Morten Ring Eskildsen, Mark Laver, Christof Niedermayer, Jonathan White, Cedomir Petrovic CeCoIn$_5$ is a heavy fermion type-II superconductor showing clear signs of Pauli-limited superconductivity. CeCoIn$_5$ is also very close to a magnetically ordered ground state; this can be achieved by, for instance, doping with Cd. A variety of measurements give evidence for a transition at high magnetic fields inside the superconducting state, when the field is applied either parallel to or perpendicular to the $c$ axis. In the latter case, antiferromagnetic order develops on the high-field side of the transition, with a magnetic wavevector of ($q$ $q$ 0.5), where $q$ = 0.44 reciprocal lattice units [1]. We show that this order remains as the field is rotated out of the basal plane, but that the associated moment eventually disappears above 17$^{\circ}$, indicating that anomalies seen with the field parallel to the $c$ axis are not related to this magnetic order [2]. Our measurements emphasise the fragility of this magnetic order.\\[4pt] [1] M. Kenzelmann et al., Science 321, 1652 (2008).\\[0pt] [2] E. Blackburn et al., Phys. Rev. Lett. 105, 187001 (2010). [Preview Abstract] |
Monday, March 21, 2011 12:51PM - 1:03PM |
B22.00009: Electronic inhomogeneity in heavy Fermions Zachary Fisk, Eric Bauer, Yi-feng Yang, Cigdem Capan, Filip Ronning, Joe Thompson, Roman Movshovich, Andrea Bianchi, Ricardo Urbano, Hironori Sakai The experimentally determined superconducting condensation energy of La-doped CeCoIn$_{5}$ is interpreted to show that the superconducting fraction decreases linearly with La concentration, consistent with the measured residual normal fraction seen in the electronic specific gamma remaining in the superconducting state as T $\to $ 0K. The In NQR data is also discussed. Our result points to an electronically inhomogeneous state that appears to be common to doped heavy Fermion materials near a quantum critical point. [Preview Abstract] |
Monday, March 21, 2011 1:03PM - 1:15PM |
B22.00010: Cooperative Intermediate Valence and Anomalous Stability of the Kondo Lattice in Ce$_{1-x}$Yb$_{x}$CoIn$_{5}$$^{\ast}$ R.E. Baumbach, L. Shu, M. Janoschek, E. Gonzales, K. Huang, T.A. Sayles, J.J. Hamlin, D.A. Zocco, C.A. McElroy, M.B. Maple, J. Paglione, P.-C. Ho, J.R. O'Brien We have investigated the chemical substitution series Ce$_{1-x}$Yb$_{x}$CoIn$_{5}$ ($0\leq x \leq1.0$) by means of X-ray diffraction, energy dispersive X-ray, specific heat, electrical resistivity, and magnetic susceptibility measurements. As Yb is substituted for Ce, the lattice constants remain roughly constant up to $x=0.775$, contrary to Vegard's law, after which phase separation is observed for $0.8 \leq x <1$. The superconducting transition temperature shows only a weak linear suppression with increasing $x$, while the coherence temperature remains constant up to $x = 0.775$. We also observe non-Fermi-liquid behavior for $0 \leq x \leq 0.775$ which is sensitive to the exact value of $x$, although there is no indication for a quantum critical point in the $T-x$ phase diagram. These results suggest that the Ce and Yb ions adopt cooperative intermediate valence states which preserve the Kondo lattice behavior and SC, while the associated valence fluctuations lead to strong modifications in the non-Fermi-liquid behavior as a function of $x$. [Preview Abstract] |
Monday, March 21, 2011 1:15PM - 1:27PM |
B22.00011: Scanning tunneling microscopy and spectroscopy measurements of heavy fermion compound CeCoIn$_{5}$ Eduardo da Silva Neto, Pegor Aynajian, Colin Parker, Paul Tobash, Eric Bauer, Ali Yazdani The heavy fermion compound CeCoIn$_{5}$ has a rich electronic phase diagram as a function of doping, pressure, and magnetic field. The interaction between Ce's f-electrons and the conduction bands is expected to form Kondo screening of the spins starting at relatively high temperatures. Below 2.3 K CeCoIn$_{5}$ is known to exhibit an unconventional superconducting ground state. We present scanning tunneling microscopy and spectroscopy (STM/S) as a function of temperature on CeCoIn$_{5}$. The in-situ cleaved samples show three different layer terminations. Acquiring structural information from STM topographies we identify the chemical character of each layer. STS measurements, on all surfaces, performed over a wide range of temperature show the rapid development of an energy gap in the tunneling density of states near the onset of coherence ($\sim $ 40 K). The origin of the observed energy gap and its relation to heavy band hybridization is addressed. [Preview Abstract] |
Monday, March 21, 2011 1:27PM - 1:39PM |
B22.00012: Electron-spectroscopy of the heavy fermion alloy Ce$_{1-x}$Yb$_x$CoIn$_5$ L. Dudy, J.W. Allen, J. Denlinger, L. Shu, M. Janoschek, R.E. Baumbach, M.B. Maple Ce$_{1-x}$Yb$_x$CoIn$_5$ (YbCe115) is a new 115 alloy series with long range magnetic order suppressed in the whole substitution range. Measurements reveal a rich phase diagram in which the Kondo lattice is robust against Yb substitution, superconductivity persists to high values of x, and the non-Fermi-liquid behavior is enhanced by Yb substitution [1].We have characterized the electronic structure of this new alloy by x-ray and angle resolved photoemission spectroscopy (XPS and ARPES) performed at the Advanced Light Source (ALS). Yb 4f XPS spectra vary with increasing x from dominantly Yb$^{3+}$ to a mix of Yb$^{3+}$ and Yb$^{2+}$, in agreement with inferences from the magnetic susceptibility [1]. We will present ARPES data to show the x-dependence of the Fermi surface and discuss the relation of the electronic structure to the transport properties. The effect of surface contributions to the XPS and ARPES data will be assessed. \\[4pt] [1] Lei Shu et al, to be published [Preview Abstract] |
Monday, March 21, 2011 1:39PM - 1:51PM |
B22.00013: The Fermi surface of CePt$_{2}$In$_{7}$: a two-dimensional analog of CeIn$_{3}$ Moaz Altarawneh, Neil Harrison, Ross McDonald, Fedor Balakirev, Charles Mielke, Paul Tobash, Jian-Xin Zhu, Joe Thompson, Filip Ronning, Eric Bauer We report magnetic quantum oscillations in magnetic fields extending to $\sim$60 T in single crystals of the body-centered tetragonal antiferromagnetic CePt$_{2}$In$_{7}$ recently discovered to exhibit pressure- induced superconductivity at $T_{c}$ = 2.1 K. Despite two-dimensionality of its Fermi surface, the microscopic electronic properties of layered CePt$_{2}$In$_{7}$ are revealed to be more similar to cubic CeIn$_{3}$ than layered CeRhIn$_{5}$. A significant field-induced change in the Fermi surface occurs at $H_{m}$ around 45 T in both CePt$_{2}$In$_{7}$ and CeIn$_{3}$, below which it is broken into small pockets with field-dependent effective masses -signaling 4f-electron involvement in the Fermi surface for $H < H_{m}$. Our findings suggest that CePt$_{2}$In$_{7}$ and CeIn$_{3}$ differ solely by the dimensionality of their Ce sublattices, thus realizing an ideal pair of compounds for investigating the effect of dimensionality on boosting superconductivity. [Preview Abstract] |
Monday, March 21, 2011 1:51PM - 2:03PM |
B22.00014: Tuning the Quantum Critical Points in CeCoIn$_{5}$ and CeRhIn$_{5}$ Through Pt Doping: Synthesis, Single Crystal and Physical Property Studies Paul Tobash, Krzysztof Gofryk, Filip Ronning, Joe Thompson, Stanislav Stoyko, Arthur Mar, Eric Bauer The well known CeCoIn$_{5}$ and CeRhIn$_{5}$ compounds provide an excellent opportunity for understanding the physics of heavy fermion superconductivity as well as quantum criticality in correlated electron intermetallics. Besides using hydrostatic pressure as a means to tune the physics of these materials, chemical doping has also proved essential for moving through the superconducting/magnetic boundary in these materials. We extend chemical substitution in CeCoIn$_{5}$ and CeRhIn$_{5}$ to another transition metal, Pt, and report on the synthesis, structure, and physical properties of single crystals of CePt$_{x}$Co$_{1-x}$In$_{5}$ and CePt$_{x}$Rh$_{1-x}$In$_{5}$. Single crystal X-ray diffraction confirmed the tetragonal structure of both systems which crystallize with the $P$4/\textit{mmm} space group and are derivatives of the parent compounds CeCoIn$_{5}$ and CeRhIn$_{5}$, respectively. We report the physical property measurements, which include magnetic susceptibility, heat capacity, and electrical resistivity. [Preview Abstract] |
Monday, March 21, 2011 2:03PM - 2:15PM |
B22.00015: Quantum criticality and Fermi surface topology in CeRhIn$_5$ H.Q. Yuan, L. Jiao, J.L. Zhang, Y. Kohama, M. Jaime, J. Singleton, E.D. Bauer, Han-Oh Lee, T. Park, J.D. Thompson In the heavy fermion compound CeRhIn$_5$, superconductivity occurs upon partially suppressing the antiferromagnetic state via applying pressure. At the quantum critical point ($p_c$=2.3GPa), observations of a Fermi surface change from a small Fermi volume to a large one [1] seems to favor the scenario of local quantum criticality [2]. In this talk, we will present the first experimental evidence of a magnetic field induced quantum phase transition in CeRhIn$_5$ by measuring the ac specific heat and the de Hass van Alphen effect using the facilities of pulsed magnetic field at Los Alamos. The antiferromagnetic transition of CeRhIn$_5$ is eventually suppressed at a critical field of $H_c\simeq 50$ T. A dramatic change of the Fermi surface is found close to $H_c$, but still on the antiferromagnetic side. At sufficiently low temperatures, the Fermi surface in the antiferromagnetic state undergo a topological change from a small Fermi volume to a large one with increasing magnetic field, the latter being kept unchanged in the paramagnetic state at fields above $H_c$. These findings seem to support a different scenario for the field induced quantum phase transition in CeRhIn$_5$, e.g., the spin-density-wave-type quantum criticality. [1] H. Shishido et. al., J. Phys. Soc. Jpn. 74, 1103 (2005). [2] Q. Si et al., Nature 413, 804 (2001). [Preview Abstract] |
Follow Us |
Engage
Become an APS Member |
My APS
Renew Membership |
Information for |
About APSThe American Physical Society (APS) is a non-profit membership organization working to advance the knowledge of physics. |
© 2024 American Physical Society
| All rights reserved | Terms of Use
| Contact Us
Headquarters
1 Physics Ellipse, College Park, MD 20740-3844
(301) 209-3200
Editorial Office
100 Motor Pkwy, Suite 110, Hauppauge, NY 11788
(631) 591-4000
Office of Public Affairs
529 14th St NW, Suite 1050, Washington, D.C. 20045-2001
(202) 662-8700