Events
Condensed Matter Seminar
Electron-Spin Resonance with Scanning Tunneling Microscopy of non-Paramagnetic Species.
Mr. Zion Hazan
BGU
Mon, 05 Jun 2023, 11:10
Sacta-Rashi Building for Physics (54), room 207
Abstract: The Electron Spin Resonance-Scanning Tunneling Microscopy (ESR-STM) experimental method combine the atomic resolution capability of STM with the spectral resolution of ESR. Except that, instead of 107 spins required for detected signal in macroscopic ESR experiment, in ESR-STM we can extract the same (and sometimes more detailed) results from single spin localized underneath the STM tip.
ESR-STM experiments has presented measurement of the right Larmor frequency of single electrons localized in SiO2 defects, BDPA radical and atoms such as Fe. Moreover, hyperfine coupling with 14N in TEMPO radical and of Ti isotopes also were reported.
However, species without an unpaired electron are yet to be measure. Here we will report the ability to ionize the molecule or atom with the STM bias voltage and thus to study the radical ion magnetic properties.
The first demonstration of ESR-STM on the non -paramagnetic molecules: C60 and L- Glutamic acid (Glu), will be presented. Moreover, the ability to ionize an atom or a molecule for a short time can lead to a change in the intensity of the hyperfine peaks – at frequency of the nuclear Larmor frequency.
Thus, we extend those findings to study the NMR-STM spectrum of different molecules.
References
[1] Hazan, Z., Averbukh, M., & Manassen, Y. (2023). ESR-STM on Diamagnetic Molecule: C60 on graphene. Journal of Magnetic Resonance, 107377.
[2] Manassen, Y., Averbukh, M., Hazan, Z., Piuzi, P. B. B., & Horovitz, B. Single spin NMR (NMR1).
[3] Manassen, Y., Jbara, M., Averbukh, M., Hazan, Z., Henkel, C., & Horovitz, B. (2022). Tunnel current noise spectra of spins in individual dimers of molecular radicals. Physical Review B, 105(23), 235438.
Particles and Fields Seminar
Nuclear aspects of neutrino interactions in oscillation experiments
Dr. Adi Ashkenazi
TAU
Mon, 05 Jun 2023, 14:00
Sacta-Rashi Building for Physics (54), room 207
Abstract: The ability of current and next generation accelerator based neutrino oscillation measurements to reach their desired sensitivity and provide new insight into the nature of our Universe, requires a high-level of understanding of the neutrino-nucleus interactions. These include precise estimation of the relevant cross sections and the reconstruction of the incident neutrino energy from the measured final state particles. Incomplete understanding of these interactions can skew the reconstructed neutrino spectrum and thereby bias the extraction of fundamental oscillation parameters and searches for new physics.
This talk will review the Tel Aviv neutrino group work to leverage charged and neutral lepton scattering data to improve the neutrino-nuclei interaction models.
Special seminar
Global Phase Diagram of Monolayer Graphene at nu=0
Prof. Ganpathy Murthy
University of Kentucky
Tue, 06 Jun 2023, 13:00
Sacta-Rashi Building for Physics (54), room 207
Abstract: Graphene, a two-dimensional honeycomb lattice of Carbon atoms, has many fascinating mechanical and electronic properties. In the presence of a strong perpendicular magnetic field, it forms nearly four-fold degenerate Landau levels (with two spins and two valleys). When an integer number of these four Landau levels are filled, the system becomes a quantum Hall ferromagnet in the spin/valley space. The ordering of the ferromagnet is determined by the interactions. In this talk I will present the history of experimental and theoretical work on this problem at charge neutrality. I will end with our contribution, which considers the most general possible interactions at low energies, and provide a set of possible phase diagrams for this problem.
Physics Colloquium
How to measure entropy in mesoscopic systems
Prof. Eran Sela
Tel-Aviv University
Tue, 06 Jun 2023, 15:15
Ilse Katz Institute for Nanoscale Science & Technology (51), room 015
Abstract: Entropy is a key characteristic of states of matter, but its measurement is typically limited to bulk systems. For this reason measurements of nontrivial entropy signatures reflecting correlations and frustration in various exotic excitations in condensed matter systems, such as Kondo impurities and Majorana states, have remained elusive. In this talk I will discuss recent experimental progress in measuring entropy in mesoscopic systems, using charge sensors of quantum dot type systems combined with thermodynamic Maxwell relations. I will show some encouraging experimental results opening the door for novel entropic probes, along with experimental puzzles.
Astrophysics and Cosmology Seminar
Polarized emission from X-ray pulsars as seen by the IXPE observatory
Dr. Sergey Tsygankov
University of Turku
Wed, 07 Jun 2023, 11:10
Sacta-Rashi Building for Physics (54), room 207
Abstract: Analysis of the polarization of electromagnetic radiation, or polarimetry, is a unique tool that allows us to obtain information about astrophysical objects that cannot be obtained in other ways, for example, regarding their geometry. With the launch of the IXPE (Imaging X-ray Polarimetry Explorer) mission at the end of 2021, this instrument became available in the X-ray range as well. In my talk I will give a brief overview of the results obtained during the first year of IXPE observations of accreting X-ray pulsars (XRPs). It was found that in all observed XRPs, the measured value of the degree of polarization is below 15%, which is much less than the theoretically predicted values. In some pulsars, it was possible to study in detail the variations in the degree of polarization and the polarization angle as a function of the rotation phase of the neutron star, which, in turn, made it possible to determine the geometric parameters of the system. I will briefly discuss physical mechanisms that could potentially explain the relatively low degree of polarization in XRPs.
Astrophysics and Cosmology Seminar
How do the most luminous black holes accrete and expel gas?
Dr. Matthew Liska
Harvard
Wed, 07 Jun 2023, 16:10
Remote Zoom Seminar
Abstract: The gravitational pull of a black hole attracts gas and forms a physical laboratory whose extreme conditions cannot be replicated on Earth. The infalling gas forms an accretion disk where the interplay between hydromagnetic processes and the warping of space-time releases gravitational energy in the form of radiation, relativistic jets, and winds. It is likely that most gas falls into supermassive black holes when the accretion rate approaches the Eddington limit (L=Ledd), at which point radiation pressure overcomes gravity. To date, our knowledge of such `luminous’ black hole accretion disks mostly relies on semi-analytical models, supplemented by a very limited set of numerical simulations. In my talk I will discuss new insights gained from the first radiative general relativistic magnetohydrodynamics (GRMHD) simulations of luminous accretion disks. I will demonstrate that magnetic fields lead to the formation of a hot corona and that misalignment between the disk and black hole spin axis can explain quasi-periodic oscillations, which have remained a mystery for over 30 years. I will finish my talk by discussing the opportunities the next-generation of GRMHD simulations bring in addressing physical processes driving spectral variability in accreting black holes.
Physics Colloquium
Using quantum technologies and quantum information theory methods for studying lattice gauge theories
Prof. Erez Zohar
The Hebrew University of Jerusalem
Tue, 13 Jun 2023, 15:15
Ilse Katz Institute for Nanoscale Science & Technology (51), room 015
Abstract: While the road to a full scale universal quantum computer is still long, in the last decades an enormous progress has been made along it. In particular, new techniques for complex many-body quantum systems based on concepts from quantum technology and information are nowadays available, allowing one to study non-perturbative, strongly correlated physics, using current technologies.
In my talk I will focus on two such approaches - quantum simulation and tensor network states. The first suggests building non-universal quantum devices which mimic the dynamics of quantum man-body models, and the latter to use the power of entanglement to significantly simplify the study of quantum models on classical computers. In particular, I will demonstrate how these tools can be applied for studying lattice gauge theories, aiming (in the long term) at open questions in particle physics.
All events
Google calendar
