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Condensed Matter/Biophysics Seminars
Fall 2019

Condensed Matter/Biophysics Seminars are in Room NPB 2205
on Mondays @ 4:05 pm t0 4:55 pm

Contact: Yasu Takano or Dmitrii Maslov

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August 26      

 

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September 2 (No seminar – Labor Day)     

 

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September 9      

 

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Kathryn McGill (UF)

 

Title

Two-dimensional materials: from Berry curvature to wrapping a microsphere

 

Abstract

The study of atomically-thin, truly two-dimensional (2D) materials has morphed into its own field since the experimental isolation of graphene and similar 2D materials in 2005. Graphene, as a single layer of carbon atoms with a unique band structure, and monolayer molybdenum disulfide (MoS2), a three-atom-thick semiconductor, have been of particular interest both for the physics accessible in 2D crystals and the applications achievable with highly flexible materials. Here I present a variety of experiments exploring the optoelectronic and mechanical properties of both monolayer MoS2 and graphene. In particular, I will discuss three studies: (1) the experimental realization of the valley Hall effect, an effect based on the Berry curvature of a material's energy bands, in monolayer MoS2; (2) methods for directly measuring the bending stiffness of graphene (and related 2D materials); and (3) an investigation of the wrapping of micro-spherical droplets by monolayer MoS2. I will conclude by discussing the future outlook of both "valleytronics" and microencapsulation by atomically thin materials.

 

Host

Amlan Biswas


September 16      

 

Speaker

Laura Fanfarillo (SISSA and UF)

 

Title

Unconventional superconductivity and Hund's induced electron correlations: a cooperative mechanism

 

Abstract

Thirty years of research has established the emergence of a new paradigm in which strong electron-electron correlations and superconductivity are strongly intertwined. A number of successful approaches have improved our understanding of this link in high-temperature copper-based superconductors and in other families, including the iron-based materials. However, a general framework to understand how superconductivity emerges in systems dominated by electron-electron repulsion is still lacking.

In this talk I will focus on the analysis of this problem in the context of iron-based superconductors. First I will provide a brief overview of the experimental evidences of the strong orbital-dependent electronic correlations characterizing the paramagnetic phase of iron-based superconductors and I will discuss this phenomenology in terms of Hund's metal physics. Then, I will present our results on the role of those electronic correlations on the superconductivity driven by a generic weak-coupling mechanism (e.g. the coupling to a boson). The key novelty of the study is the inclusion of the dynamical properties that make a Hund's metal substantially different with respect to both a weakly interacting metal and to an ordinary correlated metal with a large effective mass renormalization. This allows us to unveil the crucial role of the redistribution of spectral weight of the Hund's metal to promote superconductivity and to enhance the orbital-selective character of the gap functions.

 

Host

Peter Hirschfeld


September 23      

 

Speaker

BingKan Xue (UF)

 

Title

Associative memory, attractor dynamics, and neural networks

 

Abstract

I will describe some basic ideas in the theoretical study of neural networks, originating from the classic work of Hopfield. The Hopfield model provides an abstract characterization of associative memory, the ability of a neural network to retrieve stored patterns. In this model, memories are encoded as attractors of the network dynamics. The analogy to statistical mechanics allows us to understand the behavior of the network, whereas the biological context brings new types of questions, such as the network's capacity for storing different memories. The idea has since then been developed and generalized in many ways. I will describe some recent developments that incorporate temporal structures, such as transition between attractors and recognition of dynamic patterns, or spatial structures, such as spatial maps of environments and assembly of macro-molecules.

 

Host

Steve Hagen


September 30      

 

Speaker

Matthew Matheny (Caltech)

 

Title

Applications of nanomechanical lattices: from dynamics to computation

 

Abstract

Nanomechanical systems have been studied for over 20 years with most efforts only exploring a single resonant device at a time. Due to the current limitations in nanoscale fabrication, it proves nearly impossible to achieve the uniformity required to study even basic lattice models using nanomechanics. Here I will describe an experiment based on piezoelectric nanomechanical systems which achieves strong uniformity of lattice parameters. Amazingly, this experimental system is able to spontaneously generate exotic symmetry breaking states akin to those found in spin systems in condensed matter. I will also describe how the experimental architecture could be used for novel computational schemes. Finally, I will describe a proposed effort to use piezoelectric nanomechanics in quantum computational architectures.

 

Host

Yoonseok Lee


October 7      

 

Speaker

Manh-Huong Phan (USF)

 

Title

Two-dimensional magnetism: new discoveries, opportunities and challenges

 

Abstract

Two-dimensional (2D) magnetic van der Waals materials and their heterostructures are emerging candidates for ultralow-power and ultra-compact spintronic device applications. Although the Mermin-Wagner theorem predicts suppression of long-range magnetic order at finite temperatures in such 2D materials, recent experiments have demonstrated the existence of long-range ferromagnetic ordering in bulk van der Waals materials at the single layer limit [1,2]. In particular, our recent discovery of the strong room temperature ferromagnetism in epitaxially grown transition metal dichalcogenide (TMD) monolayers of VSe2 grown on various van der Waals substrates (graphene, graphite, MoS2, WS2) has the potential to transform the fields of spintronics and quantum computing [3]. In this talk, I will present research progress in 2D magnetism, including our new findings of tunable exchange bias effect and room temperature light-controlled magnetism in monolayer VSe2/MoS2 or VSe2/WS2 heterostructures, as well as the development of a new class of highly sensitive magnetic sensor using this single layer magnet. Opportunities and challenges in 2D magnetic materials research will be discussed .

[1] C. Gong et al., Nature 546, 265 (2017). [2] B. Huang et al., Nature 546, 270 (2017). [3] M. Bonilla et al., Nat. Nanotech. 13, 289 (2018).

 

Host

Mark Meisel


October 14      

 

Speaker

Xiaoyu Wang (NHMFL, Tallahassee)

 

Title

TBA

 

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Host

Dmitrii Maslov, Yuxuan Wang


October 21      

 

Speaker

Dixit Purushottam (UF)

 

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TBA

 

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Dmitrii Maslov


October 28      

 

Speaker

Philip Feng (UF Electrical & Computer Engineering)

 

Title

Emerging semiconductor nanoscale devices and systems for classical and quantum information processing

 

Abstract

Emerging semiconductors, ranging from atomic layer semiconducting crystals (such as transition metal dichalcogenides (TMDCs) and black phosphorus) to wide and ultrawide bandgap materials (such as SiC and Ga2O3), along with their heterostructures, offer compelling new platforms for electronic, photonic devices and transducers, where the unconventional and unique properties of these crystals can be harnessed for engineering both classical and quantum signal processing and sensing schemes.  In this presentation, I will describe some of my research group’s latest endeavors and results on advancing solid-state device physics and engineering, by employing some of these emerging semiconductors.  In classical domain, we build atomically thin transistors, optoelectronic devices, and a new class of nanoscale transducers, 2D nanoelectromechanical systems (NEMS), all enabled by 2D semiconductors and their van der Waals heterostructures.  We demonstrate how the unconventional properties of these structures and their internal strong coupling effects have led to novel transistors and logic circuits, optoelectronic devices, and resonant NEMS transducers with remarkably broad dynamic range and electrical tunability, as well as new phenomena and device functions.  Toward quantum engineering, atomistic defects in SiC and emerging 2D crystals support single-photon quantum emitters promising for enabling quantum bits (qubits) at room temperature.  Built on our recent attainments in SiC photonics and 2D devices, we explore such platforms and heterogeneous integration, toward realizing quantum transduction and information processing in chip-scale integrated systems.

 

Host

Yoonseok Lee


November 4      

 

Speaker

Mathias Scheurer

 

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Host

Yuxuan Wang


November 11 (No seminar – Veterans Day)     

 

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November 18        

 

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Adrian H. C. Po (MIT)

 

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TBA

 

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Host

Yuxuan Wang


November 25 (Monday of Thanksgiving Week)        

 

Speaker

Alex Levchenko (Uni. Wisconsin--Madison)

 

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TBA

 

Abstract


 

Host

Dmitrii Maslov


December 2 (Monday after Thanksgiving Holiday)      

 

Speaker

Rongying Jin (Louisiana State Univ.)

 

Title

TBA

 

Abstract


 

Host

Xiaoguang Zhang

 

Physics Home

Condensed Matter/Biophysics Seminars
Spring 2020

Condensed Matter/Biophyics Seminars are in Room NPB 2205
on Mondays @ 4:05 pm t0 4:55 pm

Contact: Yasu Takano or Dmitrii Maslov

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January 6      

 

Speaker

Thomas Searles (Howard Univ.)

 

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Host

Chris Stanton


January 13       

 

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Juan Guan (UF)

 

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Host

Dmitrii Maslov


January 20 (No seminar - Martin Luther King Jr. Day)      

 

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January 27      

 

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Constantin Schrade (MIT)

 

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Dominique Laroche


February 3   

 

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February 10      

 

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February 17  

 

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February 24      

 

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March 2 (No Seminar - UF Spring Break Week, APS March Meeting in Denver)

 

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March 9      

 

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March 16       

 

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March 23       

 

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Se Kwon Kim (Univ. Missouri)

 

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Yoonseok Lee


March 30    

 

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April 6      

 

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Alimamy Bangura (NHMFL, Tallahassee)

 

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Mark Meisel


April 13      

 

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April 20      

 

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