Condensed Matter / Biophysics Seminars |
Fall 2022 |
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Condensed Matter/Biophysics Seminars
Mondays at 4:05pm in 2205 NPB
Committee: Yuxuan Wang, Xiao-Xiao Zhang and Purushottam Dixit |
August 29 |
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September 5 |
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September 12 |
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September 19 |
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September 26 |
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October 3 |
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| Speaker | Chunjing Jia (UF Physics) | |
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October 10 |
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| Speaker | Andrey Chubukov (UMN) | |
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| Host | Yuxuan Wang | |
October 17 |
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| Speaker | Armita Nourmohammad (University of Washington) | |
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October 24 |
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| Speaker | Richard Greene (University of Maryland) | |
| Title | Strange metal transport, ferromagnetism and the Planckian scattering rate limit in electron-doped cuprates | |
| Abstract | I will discuss recent transport studies on thin films of the electron-doped cuprate system La2-xCexCuO4 that exhibit strange metal transport in the normal state down to 35 mK. These results strongly suggest that the high-Tc superconductivity emerges from this strange metal normal state. The strange metal behavior is manifested as a linear-in-T resistivity from 35 mK to 20K and a ~T^2 resistivity from 50K to 400K over a range of doping above and below a Fermi surface reconstruction at x = 0.14 [1-2]. Other indications of strange metal behavior include a low temperature linear-in-H magnetoresistance and a low temperature lnT thermopower [3-5] over the same range of doping. At the present time these results have not been explained and they represent a challenge to the theory of the cuprates.
In addition, I will discuss a study of these films via a combination of dc conductivity and optical conductivity [6], which shows that the electron scattering rate far exceeds the conjectured Planckian bound on inelastic scattering at temperatures above 20K. This suggests that recent highly publicized claims of a Planckian bound on transport in solids are not universal and that the temperature dependence of the normal state resistivity of the cuprates remains an unexplained mystery. If time permits I will discuss experiments that suggest ferromagnetism exists below 4K for electron-doping beyond the superconducting dome [7]. References [1]. T. Sarkar et al., Phys. Rev. B 103, 224501 (2021) [2]. T. Sarkar et al., Phys. Rev. B 98, 224503 (2018) [3]. R. L. Greene et al., Ann Rev Cond. Matt. Phys. 11, 213 (2020) [4]. T. Sarkar et al., Sci. Adv. 5, eeav6753 (2019) [5]. P. R. Mandal et. al., PNAS 116, 5991 (2019) [6]. N. R. Poniatowski et al., Phys. Rev. B 104, 235138 (2021) [7]. T. Sarkar et al., Science 368, 532 (2020). |
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| Host | David Tanner and Peter Hirschfeld | |
October 31 |
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| Speaker | Qiong Yang (University of Michigan) | |
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November 2 - SPECIAL SEMINAR |
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| Speaker | Daniel Rhodes, MSE & Physics, University of Wisconsin-Madison | |
| Title | Moving Beyond Graphene and 2D Semiconductors: Superconductivity and Ferroelectricity in Few-Layer Td-MoTe2 | |
| Abstract | 2D materials are layered materials that may be readily exfoliated down to a single atomic layer, presenting an opportunity to control electronic states and magnetic ordering noninvasively and efficiently. In this talk, I discuss the materials challenges faced by the 2D community in exploring novel 2D materials beyond graphene and 2D transition metal dichalcogenide semiconductors. The materials challenges are not trivial to solve, and meaningful solutions must include complete control over material synthesis and device fabrication, in combination with contact engineering. After discussing these challenges, I will follow up an example material (Td-MoTe2), whereby solutions to the materials challenges allow us to probe how topology emerges from the bulk down to monolayer thicknesses for Td-MoTe2. We will explore how the influence of an electrostatic gate allows us to identify a unique superconducting state in bilayer Td-MoTe2 and its profound influence even when no change in the chemical potential is made. Our results indicate that superconductivity in bilayer Td-MoTe2 can be completely quenched by an electrostatic gate, and that the superconducting behavior is connected to Fermi surface nesting between electron and hole pockets. Not only, because of the monoclinic crystal structure ferroelectric behavior is established and its effects on superconductivity investigated. | |
| Host | Xiao-Xiao- Zhang | |
November 7 |
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| Speaker | Alexander Balatsky (U. Connecticut) | |
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| Host | Peter Hirschfeld | |
November 9 - Special Seminar at 2pm in 2260 |
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| Speaker | Brian Cowan (Royal Holloway College) | |
| Title | NMR as a probe of many body dynamics and collective excitations | |
| Abstract | Nuclear Magnetic Resonance Techniques are proving to be a especially valuable for probing many modern many body problems from fluctuations in unconventional superconductivity to the fundamental dynamics of quantum fluids at very low temepratures. The talk will review the NMR theory that probes collective behaviors along with modern examples. | |
| Host | Neil Sullivan | |
November 14 |
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| Speaker | Li Fang (UCF) | |
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| Host | Xiao-Xiao Zhang | |
November 21 |
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November 28 |
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| Speaker | Daniel Weissman (Emory) | |
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December 5 |
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| Speaker | Andriy Nevidomskyy (Rice) | |
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| Host | Peter Hirschfeld | |
December 12 |
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Condensed Matter / Biophysics Seminars |
Spring 2023 |
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Condensed Matter/Biophysics Seminars
Mondays at 4:05pm in 2205 NPB
Committee: Yuxuan Wang, Xiao-Xiao Zhang and Purushottam Dixit |
January 9 |
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January 16 |
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January 23 |
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| Speaker | Rahul Nandkishore (CU-Boulder) | |
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January 30 |
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February 6 |
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February 13 |
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February 20 |
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February 27 |
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| Speaker | Prof Na Hyun Jo (University of Michigan) | |
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| Host | Yoon Lee | |
March 6 |
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March 13 |
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March 20 |
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March 27 |
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| Speaker | Xiao-Xiao Zhang (UF Physics) | |
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| Host | Yoonseok Lee | |
April 3 |
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| Speaker | BingKan Xue | |
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| Host | Xiaoguang Zhang | |
April 10 |
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