Bulletin of the American Physical Society
APS March Meeting 2019
Volume 64, Number 2
Monday–Friday, March 4–8, 2019; Boston, Massachusetts
Session K17: Matter in Extreme Environments: Quantum MaterialsFocus
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Sponsoring Units: DCOMP Chair: Bianca Haberl Room: BCEC 156A |
Wednesday, March 6, 2019 8:00AM - 8:36AM |
K17.00001: Physics of Ultra-light Materials Under Pressure: Quantum and isotope effects in lithium metal Invited Speaker: Shanti Deemyad In this talk I will discuss the physics of ultra-light materials and evolution of quantum effects under extreme pressures. In periodic table lithium is the first element immediately after helium and the lightest metal. While fascinating quantum nature of condensed helium is suppressed at high densities, because of the presence of long range interactions in metallic systems, lithium is expected to adapt more quantum solid behavior under compression. Physics of dense lithium offers a rich playground to look for new quantum phenomena in condensed matter. I will discuss the presence of quantum contributions to the structural phase transitions of lithium at low temperature and will present our results on resolving the long lasting mystery of lithium ground state1,2. |
Wednesday, March 6, 2019 8:36AM - 8:48AM |
K17.00002: Electronic and Optical Properties of SnO2 at High Pressure Nathan Dasenbrock-Gammon, Ranga P Dias, Elliot Snider Tin oxide (SnO2) is one of the most widely used n-type transparent conducting oxide materials, which has attracted increasing interest due to its outstanding electrical and optical properties for potential applications. We present a detailed investigation on pressure-induced structural, electronic, and optical transitions of SnO2 to 60 GPa, using a diamond anvil cell, micro-confocal Raman spectroscopy, infrared absorption, reflectivity, and electrical resistance measurements. The results indicate that a wide band gap (Eg=3.6 eV) n-type semiconductor undergoes a semiconductor to insulator transition at ~18 GPa. Furthermore, we will present the temperature dependent resistance changes and photoconductivity with different power density at high pressures. |
Wednesday, March 6, 2019 8:48AM - 9:00AM |
K17.00003: WITHDRAWN ABSTRACT
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Wednesday, March 6, 2019 9:00AM - 9:12AM |
K17.00004: ABSTRACT WITHDRAWN
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Wednesday, March 6, 2019 9:12AM - 9:24AM |
K17.00005: Pressure-induced superconductivity in weak topological insulator Bi2TeI and topological metal Bi3TeI Derrick VanGennep, You Lai, Yogesh Kumar Vohra, Samuel T Weir, Ryan Baumbach, James J. Hamlin Using a newly developed system designed to rapidly screen materials for pressure-induced superconductivity we have performed a series of high pressure electrical transport and ac magnetic susceptibility measurements on single crystals of the weak topological insulator Bi2TeI and the topological metal Bi3TeI. Upon compression at low temperature, we find that Bi2TeI becomes superconducting at ∼13 GPa and Bi3TeI begins to superconduct at pressures above ∼11.5 GPa. The superconducting critical temperature Tc reaches maximum values of 7 K and 7.5 K for Bi2TeI and Bi3TeI, respectively. We observe distinct anomalies in the resistivity of both samples as a function of pressure, which may arise due to structural transitions. |
Wednesday, March 6, 2019 9:24AM - 9:36AM |
K17.00006: High pressure, high magnetic fields fermiology studies of YBCO. Audrey Grockowiak, William A Coniglio, Stanley W Tozer The pnictide, cuprate and molecular conductor families exhibit similar phase diagrams, leading to a great deal of interest in a common mechanism for a “universal phase diagram”. The typical ingredients for such phase diagrams include an antiferromagnetic phase, a superconducting dome, and possibly one, or several quantum critical points (QCP). Chemical doping is one traditional way to look at such materials, however thermodynamic variables such as magnetic field or hydrostatic pressure have proven to be powerful tools to explore this phase diagram, with very strong magnetic fields being used to suppress the superconducting dome, allowing one to investigate the QCP. |
Wednesday, March 6, 2019 9:36AM - 9:48AM |
K17.00007: Pressure-Induced Structural Phase Transition and Magnetic Fluctuations in CeNi Andrei Podlesnyak, Alexander I Kolesnikov, Georg Ehlers, Antonio M. dos Santos, Athena S. Sefat, Gregory J. Halder, Alex Mirmelstein The pressure-induced structural phase transition and magnetic fluctuations in the intermediate-valence compound CeNi has been investigated by x-ray and neutron scattering techniques. The observed Cmcm → Pnma structural transition is analyzed using density functional theory calculations, which successfully reproduce the ground state volume, the phase transition pressure, and the volume collapse associated with the phase transition. Equations of state for CeNi on both sides of the phase transition are derived and an approximate P-T phase diagram is suggested for P < 8 GPa and T < 300 K. The inelastic neutron scattering study of the dynamic magnetic response of CeNi reveals that the structural transition increases the characteristic energy of magnetic fluctuations due to enhanced Ce 4f - Ni 3d hybridization. At the same time, the inelastic 4f magnetic form factor remains unchanged. |
Wednesday, March 6, 2019 9:48AM - 10:00AM |
K17.00008: High Pressure Behavior of Ternary H-C-S Compounds: Structural and Electronic Properties Elliot Snider, Nathan Dasenbrock-Gammon, Ranga P Dias Efforts to identify and develop room temperature superconducting materials are an intensive area of research, motivated by both fundamental science and the prospect for applications. We present pressure-induced structural and electronic properties of ternary H-C-S compounds to 150 GPa, using a diamond anvil cell, micro-confocal Raman spectroscopy, infrared absorption, and electrical resistance measurements. The results indicate that the H-C-S compound undergoes two structural phase transitions and an insulator-metal transition above 55 GPa. The temperature dependent resistance changes further show a gradual electronic transition from an insulator to a metal, which is driven by the pressure induced band gap closing. Also, we will discuss further investigation of these compounds as potential superconductors with high transition temperatures. |
Wednesday, March 6, 2019 10:00AM - 10:12AM |
K17.00009: High pressure study on a giant magnetoelectric effect hexaferrite via neutron techniques Yan Wu, Kun Zhai, Jamie Molaison, Bianca Haberl, Young Sun, Huibo Cao Multiferroics have attracted tremendous research interests because of their potential in constructing next-generation multifunctional devices. Y-type hexaferrite Ba2Mg2Fe12O22 has promising magnetoelectric (ME) properties as a multiferroics which is sensitive to small magnetic field. When doped with Sr, the material keeps its sensitivity to field while the ME coefficients are greatly enhanced with Sr level increasing. Our previous work has reported new records of ME coefficients in single phase materials shown on Ba2Mg2Fe12O22 with Sr doping that changes its ground state spin cone symmetry. Temperature dependent neutron diffraction investigation shows pinning effect emerging at heavy Sr doped sample that also change to be an alternating longitudinal conical ground state. Applying hydrostatic pressure has different effects on these simultaneously occurred phenomena, indicating their relatively independent mechanisms. With recent progress of diamond anvil cell (DAC) at the HB-3A beamline, we are able to identify interesting pressure effect picture up 7.3 Gpa on the system magnetic states. |
Wednesday, March 6, 2019 10:12AM - 10:24AM |
K17.00010: ABSTRACT WITHDRAWN
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Wednesday, March 6, 2019 10:24AM - 11:00AM |
K17.00011: High Pressure Behaviors of Dense Planetary Mixtures Invited Speaker: Choong-Shik Yoo Hydrogen (H2) and helium (He) are two most fundamental solids abundant in the Universe. Compression behaviors of H2 and He are critical to understand many body effects of these quantum solids; develop new condensed matter theories; and get insights into the internal structure of the Giant planets. In contrast to a rapid progress in understanding the phase diagram of H2 at high pressures, a little is known about the phase behavior of planetary mixtures including the most fundamental quantum solids, H2 and He. In this talk, we will describe our recent studies on high pressure behaviors of several systems of planetary mixtures including H2-He, H2-N2, He-N2, and H2-H2O. The results underscore a significant level of mixing in these planetary mixtures and thereby strong chemical interactions of the interstitial-filled guest H2 with the host lattices of He, N2 and H2O. Based on these results we will point out several fundamental principles governing the pressure-induced phase and chemical transformations in the planetary mixtures, which include strong repulsive interaction, entropically driven phase mixing, proton exchange and ordering, and kinetic-controlled metastable phases. |
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