Session T3: DCMP/DMP Prize Session: Buckley, McGroddy, Davisson-Germer

Oliver E. Buckley Condensed Matter Prize Talk I

This abstract not available.   

Oliver E. Buckley Condensed Matter Prize Talk: High-resolution Photoemission Studies of the High Tc Superconductors

In the last decade, high resolution angle-resolved photoelectron spectroscopy has evolved into one of the most powerful probes of the electronic structure of condensed matter systems. This development reflects new technological advances coupled to the enormous research effort devoted to the study of strongly correlated systems, particularly the high T$_{c}$ cuprate superconductors. Two decades after their initial discovery the latter still present some of the biggest challenges for materials science. In this talk we review some of the developments in new instrumentation and analysis techniques in photoemission and include discussion of both self-energy effects and Fermi surface studies. In the latter case, the discussion will focus on the pseudogap phase of the underdoped cuprates with particular reference to an observed particle-hole asymmetry and the possibility of hole pockets.   

Oliver E. Buckley Condensed Matter Prize Talk: Energy Gaps and Their Implications on the Phase Diagram of Cuprate Superconductors

In this talk, I will survey the progress made in understanding the cuprate superconductors using angle-resolved photoemission spectroscopy. I will focus on the discovery and understanding of the anomalous energy gaps, and their implication on the pairing symmetry as well as the phase diagram of cuprate superconductors. This includes the detection of the d-wave superconducting gap structure that contributes to the current consensus of d-wave pairing symmetry, the unexpected discovery of the anisotropic normal state gap in single particle spectra (also known as pseudogap) that has become a defining feature of the cuprate phase diagram, the new progress in demonstrating that the pseudogap state is a distinct phase that breaks the particle-hole (thus translational) symmetry, and the momentum dependent information on the competition between pseudogap and superconducting gap.   

James C. McGroddy Prize for New Materials Talk: Geometrically Frustrated Materials

Geometrical frustration occurs when interacting degrees of freedom do not ``fit'' into the lattice that they occupy and, as a result, are under-constrained at low temperature. While the early ideas behind geometrical frustration originate in Wannier's triangular antiferromagnetic Ising model and Anderson's resonating valence bond model, they are broadened here to define an entire class of magnetic materials whose structures are based on triangular or tetrahedral units. When the degree of misfit is high, conventional long range order is suppressed and thermodynamic spectral weight is pushed to energies much lower than the mean field value. Out of this low energy spectral weight, new states of matter are found to emerge experimentally, such as spin liquid on the kagome lattice and spin ice on the pyrochlore lattice. The concept of geometrical frustration can be broadened beyond magnetism to describe a frustrated soft mode that can lead to persistent negative thermal expansion and giant dielectric constants. A brief review will be given of recent work on excitations in frustrating lattices, including the prediction of, and evidence for, magnetic monopoles in spin ice, and the relevance of frustrated hopping for topological insulators.   

Davisson-Germer Prize in Atomic or Surface Physics Talk: Soft X-Ray Studies of Surfaces, Interfaces and Thin Films: From Spectroscopy to Ultrafast Nanoscale Movies

My talk will review the development of soft x-ray spectroscopy and microscopy and its impact on our understanding of chemical bonding, magnetism and dynamics at surfaces and interfaces. I will first outline important soft x-ray spectroscopy and microscopy techniques that have been developed over the last 30 years and their key strengths such as elemental and chemical specificity, sensitivity to small atomic concentrations, separation of charge and spin properties, spatial resolution down to the nanometer scale, and temporal resolution down to the intrinsic femtosecond timescale of atomic and electronic motions. I will then present scientific breakthroughs based on soft x-ray studies in three selected areas: the nature of molecular bonding and reactivity on metal surfaces, the molecular origin of liquid crystal alignment on surfaces, and the microscopic origin of interface-mediated spin alignments in modern magnetic devices. My talk will also cover the use of soft x-rays for revealing the temporal evolution of electronic structure, addressing the key problem of ``function,'' down to the intrinsic femtosecond time scale of charge and spin configuration changes. As examples I will present the formation and breaking of chemical bonds in surface complexes and the motion of the magnetization in magnetic devices.