Bulletin of the American Physical Society
83rd Annual Meeting of the APS Southeastern Section
Volume 61, Number 19
Thursday–Saturday, November 10–12, 2016; Charlottesville, Virginia
Session D2: Metamagnetism |
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Chair: Bellave Shivaram, University of Virginia Room: Salon C |
Thursday, November 10, 2016 3:45PM - 4:15PM |
D2.00001: Harnessing the f-electron valence in ThCr$_{\mathrm{2}}$Si$_{\mathrm{2}}$-type compounds Invited Speaker: Ryan Baumbach Work during the past several decades has made it increasingly clear that unstable valence correlated electron materials (e.g., cuprates, iron-pnictide/chalcogenides, and f-electron systems) are at the frontier for discoveries. These systems exhibit extraordinary phenomena, including breakdown of Fermi liquid behavior, non-phonon mediated superconductivity, and anomalous ordered states. In spite of intense efforts to unravel their behaviors, they continue to be intractable to theoretical treatments. Equally challenging is that their chemical phase space is enormous, making brute force exploration of real materials ineffective. In this talk, I will discuss a new way to organize the abundant f-electron materials crystallizing in the ThCr$_{\mathrm{2}}$Si$_{\mathrm{2}}$-type structure, which hosts numerous exemplary correlated electron materials (e.g., the heavy fermion superconductors CeCu$_{\mathrm{2}}$Si$_{\mathrm{2}}$ and URu$_{\mathrm{2}}$Si$_{\mathrm{2}})$. In particular, I will suggest that f-electron materials in this structure are parameterized in two dimensional maps with the axes of unit cell volume and electronic concentration, where the loci of the exotic metallic states coincides with crossover regions between different f-electron valences. This picture unifies earlier work and, importantly, shows that chemical variation on the transition metal or ligand sites explores the 2D phase space along a non-trivial vector. This provides essential guidance for deciding which of these materials might host extraordinary behavior (e.g., quantum criticality, non-Fermi-liquid, anomalous magnetism, and superconductivity) and how to tune them. Importantly, it removes the need for exhaustive expeditions in the chemical phase space, which drastically improves the ability to uncover novel behavior in these and related systems. To examine this picture, I will present results for the chemical substitution series CeCu$_{\mathrm{2}}$Si$_{\mathrm{2-x}}$P$_{\mathrm{x}}$ and URu$_{\mathrm{2}}$Si$_{\mathrm{2-x}}$P$_{\mathrm{x}}$, which explore the electron doping vector in their respective phase diagrams. Particular attention will be given to the anomalous high field ordered state in URu$_{\mathrm{2}}$Si$_{\mathrm{2}}$ and how it evolves with $x$. [Preview Abstract] |
Thursday, November 10, 2016 4:15PM - 4:45PM |
D2.00002: Unusual Magnetic-Pressure Response of an $S=1$ Antiferromagnetic Linear-Chain near the $D/J \approx 1$ Critical Point $^{\ast}$ Invited Speaker: Mark W. Meisel An $S = 1$ chain, [Ni(HF$_2$)(3-Clpy)$_4$]BF$_4$ (py = pyridine), has been identified to have nearest-neighbor antiferromagnetic interaction $J/k_B = 4.86$~K and single-ion anisotropy $D/k_B = 4.3$~K, while avoiding long-range order to 25 mK.$^{\dagger}$ With $D/J = 0.88$, this system is close to the $D/J \approx 1$ gapless quantum critical point between the Haldane and Large-$D$ phases. The magnetization was studied at 50~mK $\leq T \leq~1$~K and with $B \leq 10$~T.$^{\ddagger}$ Using a magnetometer equipped with a pressure cell, the low-field (0.1~T), high temperature ($T \geq 2$~K) magnetic susceptibility was studied to 1.47~GPa. These data suggest the response at ambient pressure$\,^{\dagger}$ changes between 0.24~GPa and 0.35~GPa. These studies have been or are being extended by $^1$H NMR experiments capable of varying the pressure, inelastic neutron scattering investigations down to 300~mK, and X-ray diffraction at 300~K and with pressures up to nominally 1.5~GPa. The status of the analysis of all of the data sets will be provided.\\ $\dagger$~J.L.~Manson \emph{et al.}, Inorg.~Chem. 51 (2012) 7520. \\ $\ddagger$~J.-S.~Xia \emph{et al.}, arxiv.1409.5971 (2014).\\ $^{\ast}$~This work is a collaboration involving M.K.~Peprah, P.A.~Quintero, J.S.~Xia, Y.~Tao, X.~Zuo, J.M.~P\'erez, A.~Garcia, S.E.~Brown, S.~Lapidus, and J.L.~Manson. [Preview Abstract] |
Thursday, November 10, 2016 4:45PM - 5:15PM |
D2.00003: Metamagnetism in Heavy Electron Materials and Correlated Oxides . Invited Speaker: Bellave Shivaram Metamagnetism in itinerant magnets will be reviewed[1,2,3]. Recent nonlinear magnetization, ultrasound and magnetostriction work on heavy fermions and correalted oxides will be presented. The appeal of the `single energy scale model' developed in the context of these new measurements will be critically examined. Notable deviations from this model will be discussed. [1] "Universality in the Nonlinear Magnetic Response of Strongly Correlated Metals", B.S. Shivaram, D.G. Hinks, M.B. Maple and P. Kumar, Phys. Rev., B89, 241107(Rapid Communication), 2014. [2] "Metamagnetism and the Fifth Order Susceptibility in UPt3", B.S. Shivaram, Brian Dorsey, D.G. Hinks and Pradeep Kumar, Phys. Rev., B89, 161108(Rapid Communication), (2014). [3] ``High Field Ultrasound Measurements in UPt3 and the Single Energy Scale Model of Metamagnetism'', B.S. Shivaram, V.W. Ulrich, P. Kumar and V. Celli, Phys. Rev.B, 91, 115110, 2015. [4] ``Metamagnetism'', E. Stryjewski and N. Giordano, Advances in Physics, 26,487, (1977). a Work done in collaboration with Vittorio Celli and Gia-Wei Chern (U.Virginia), the Maple group at UCSD, A. Thamizhavel and S. Ramakrishnan (TIFR, India), and D. Phelan and U. Welp (Argonne National Labs), Marcelo Jaime (LANL) and Pradeep Kumar (U.Florida). [Preview Abstract] |
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