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Microstructural Kinetics Group

Department of Materials Science & Metallurgy
 

Thu 03 Apr 16:00: 2024 Novo Nordisk Prize Lectures

School of Physical Sciences - Wed, 05/02/2025 - 10:39
2024 Novo Nordisk Prize Lectures

Abstract not available

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Tue 11 Feb 14:00: Title to be confirmed

School of Physical Sciences - Tue, 04/02/2025 - 19:34
Title to be confirmed

Abstract not available

  • Speaker: Wendelin Werner (Cambridge)
  • Tuesday 11 February 2025, 14:00-15:00
  • Venue: MR12.
  • Series: Probability; organiser: ww295.

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Wed 30 Apr 14:00: Title to be confirmed

School of Physical Sciences - Tue, 04/02/2025 - 13:49
Title to be confirmed

Abstract not available

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Wed 28 May 11:15: Title to be confirmed

School of Physical Sciences - Tue, 04/02/2025 - 12:46
Title to be confirmed

Abstract not available

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Thu 06 Feb 17:00: Formalisation of Combinatorial Optimisation in Isabelle/HOL: Network Flows

School of Physical Sciences - Tue, 04/02/2025 - 11:51
Formalisation of Combinatorial Optimisation in Isabelle/HOL: Network Flows

Combinatorial optimisation (CO) is a sub-area of discrete mathematics. Basic examples for CO problems are finding a shortest path or a minimum spanning tree in a graph. So-called network flows or variations of matching would be more advanced problems. There are also abstract concepts like matroids that offer an algebraic point of view and a uniform foundation for some of the more concrete problems.

Since the considered structures are finite, it is a natural aim to compute a solution efficiently. That implies an overlap with the theory of algorithms, especially running time analysis.

This talk is mainly about the Isabelle/HOL formalisation of a specific CO problem, namely, minimum cost flows, which are a subtype of network flows. Among others, this includes Orlin’s Algorithm, which is a most efficient method to compute a minimum cost flow in general networks. Also, the running time argument for this advanced algorithm and some reductions among flow problems were formalised.

- The Isabelle proof scripts can be found in this GitHub repo: https://github.com/mabdula/Isabelle-Graph-Library

- The formalisation is described in this paper: A Formal Analysis of Capacity Scaling Algorithms for Minimum Cost Flows by Mohammad Abdulaziz and Thomas Ammer, ITP 2024

=== Hybrid talk ===

Join Zoom Meeting https://cam-ac-uk.zoom.us/j/87143365195?pwd=SELTNkOcfVrIE1IppYCsbooOVqenzI.1

Meeting ID: 871 4336 5195

Passcode: 541180

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Fri 14 Mar 10:30: TBC (Mini-course talk 2) Please note the unusual time and place.

School of Physical Sciences - Tue, 04/02/2025 - 11:41
TBC (Mini-course talk 2)

Abstract not available

Please note the unusual time and place.

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Thu 13 Mar 11:15: TBC (Mini-course talk 1) Please note the unusual time and place.

School of Physical Sciences - Tue, 04/02/2025 - 11:40
TBC (Mini-course talk 1)

Abstract not available

Please note the unusual time and place.

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Wed 12 Mar 16:00: TBC (Geometry Colloquium)

School of Physical Sciences - Tue, 04/02/2025 - 11:38
TBC (Geometry Colloquium)

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Wed 14 May 11:15: Title to be confirmed

School of Physical Sciences - Tue, 04/02/2025 - 10:54
Title to be confirmed

Abstract not available

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Wed 19 Mar 11:15: Title to be confirmed

School of Physical Sciences - Tue, 04/02/2025 - 10:53
Title to be confirmed

Abstract not available

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Wed 05 Mar 11:15: Emergent phenomena in nanosculpted devices of quantum materials

School of Physical Sciences - Tue, 04/02/2025 - 10:52
Emergent phenomena in nanosculpted devices of quantum materials

Electrons typically traverse a conductive medium in a diffusive manner, resulting in a linear relationship between the measured voltage and applied current – known as Ohm’s law. However, violations of Ohm’s law may be found when the inherent symmetries of the underlying system are broken. Examples include the sliding motion of density waves; ballistic or hydrodynamic electron transport; or the symmetry-breaking realised by lattice or magnetic order. Focused ion beam (FIB) fabrication methods enable precise nanoscale devices to be fashioned from high-quality single crystalline materials, ideal for exploring these nonlinear phenomena. Such nanoengineering offers vast potential for the investigation of both fundamental physics and the development novel quantum devices. In this talk, I will introduce three specific examples. Firstly, we will explore the current-induced sliding motion of a skyrmion lattice in Gd2PdSi3 and the resulting emergent electrodynamics, which originate from a time-dependent Berry phase. Secondly, I will highlight our latest breakthrough to develop FIB fabrication of three dimensional nanostructures, in the form of helical-shaped devices of the high-mobility Weyl magnet CoSn2S2. By breaking inversion symmetry on the length scale of the electron mean free path, we observe large nonreciprocal transport, resulting in a switchable diode effect. Finally, if time permits, I will discuss the possibility to fabricate highly symmetrical devices, which allows the probing of symmetry breaking along multiple directions of a material simultaneously – in this case exploited to study signatures of p-wave magnetism in Gd3Ru4Al12.

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Fri 14 Feb 14:00:  Anomalous fluctuations in stochastic cellular automata

School of Physical Sciences - Tue, 04/02/2025 - 10:00
 Anomalous fluctuations in stochastic cellular automata

Anomalous fluctuations are phenomena where hydrodynamic fluctuations in the system behave in a way that violates usual expectations, e.g. typical fluctuations that are Gaussian. It was discovered recently that certain many-body systems exhibit such fluctuations, and one of the most notable examples is the isotropic spin-1/2 Heisenberg chain whose spin transport shows a surprising “partial” Kardar-Parisi-Zhang (KPZ) physics. Such partial KPZ behaviour has been also experimentally confirmed using superconducting qubits, where it was observed that the higher spin cumulants behave in a way that is not controlled by any known KPZ sub universality class (e.g. GUE or Baik-Rains). In this talk, I will introduce a hydrodynamic framework based the ballistic macroscopic fluctuation theory to describe anomalous fluctuations and apply it to a class of stochastic cellular automata. The cellular automata, which have been solved microscopically, conserve a charge and it has been demonstrated that the charge fluctuations in these systems and the spin fluctuations in the easy-axis Heisenberg chain are both anomalous with the same non-Gaussian probability distribution function. I will show how our approach successfully reproduces the known typical and large charge fluctuations in the systems and explain how one can understand the phenomena hydrodynamically in systems with a Z_2 charge.

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Thu 15 May 14:00: Creation of Chemical Complexity via Controlled Functionalization of Organoboron Compounds

School of Physical Sciences - Tue, 04/02/2025 - 09:06
Creation of Chemical Complexity via Controlled Functionalization of Organoboron Compounds

Novel reactivities of organoboron compounds have been identified as a source for creating new chemical spaces with functional value. Previously uncharted approaches of activation including, non-covalent interactions, electrochemical redox processes, and photoexcitation have been exploited for the functionalization of organoboron compounds. Combined experimental and computational studies provide insight into the fundamental understanding of the process. Special emphasis of the research program has been devoted to the formation of products with stereochemically-enriched C(sp3) center.

References [1] Go, S. Y.; Chung, H.; Shin, S. J.; An, S.; Youn, J. H.; Im, T. Y.; Kim, J. Y.; Chung, T. D.; Lee, H. G. J. Am. Chem. Soc. 2022, 144, 9149. [2] Roh, B.; Farah, A. O.; Kim, B.; Feoktistova, T.; Moller, F.; Cheong, P. H.; Lee, H. G. J. Am. Chem. Soc. 2023, 145, 7075. [3] Koo, J.; Kim, W.; Jhun, B. H.; Park, S.; Song, D.; You, Y.; Lee, H. G. J. Am. Chem. Soc. 2024, 146, 22874.

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Wed 05 Feb 11:15: Emergent phenomena in nanosculpted devices of quantum materials

School of Physical Sciences - Tue, 04/02/2025 - 08:36
Emergent phenomena in nanosculpted devices of quantum materials

Electrons typically traverse a conductive medium in a diffusive manner, resulting in a linear relationship between the measured voltage and applied current – known as Ohm’s law. However, violations of Ohm’s law may be found when the inherent symmetries of the underlying system are broken. Examples include the sliding motion of density waves; ballistic or hydrodynamic electron transport; or the symmetry-breaking realised by lattice or magnetic order. Focused ion beam (FIB) fabrication methods enable precise nanoscale devices to be fashioned from high-quality single crystalline materials, ideal for exploring these nonlinear phenomena. Such nanoengineering offers vast potential for the investigation of both fundamental physics and the development novel quantum devices. In this talk, I will introduce three specific examples. Firstly, we will explore the current-induced sliding motion of a skyrmion lattice in Gd2PdSi3 and the resulting emergent electrodynamics, which originate from a time-dependent Berry phase. Secondly, I will highlight our latest breakthrough to develop FIB fabrication of three dimensional nanostructures, in the form of helical-shaped devices of the high-mobility Weyl magnet CoSn2S2. By breaking inversion symmetry on the length scale of the electron mean free path, we observe large nonreciprocal transport, resulting in a switchable diode effect. Finally, if time permits, I will discuss the possibility to fabricate highly symmetrical devices, which allows the probing of symmetry breaking along multiple directions of a material simultaneously – in this case exploited to study signatures of p-wave magnetism in Gd3Ru4Al12.

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Fri 07 Feb 13:00: Unimodular JT gravity and de Sitter quantum cosmology

School of Physical Sciences - Mon, 03/02/2025 - 18:51
Unimodular JT gravity and de Sitter quantum cosmology

In this talk, I will show how a gauge-theoretic approach to Jackiw–Teitelboim (JT) gravity naturally yields a two-dimensional Henneaux–Teitelboim (HT) unimodular theory, applicable to both flat and curved spacetimes. Under a mini-superspace reduction, the Wheeler–DeWitt equation becomes a Schrödinger-like equation admitting a consistent, unitary quantum description. The resulting wavefunction describes a quantum distribution for the scale factor, illuminating cosmic expansion and contraction, and allowing topology change at a=0.

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Fri 07 Feb 16:00: Flavour Physics Beyond the Standard Model with the SMEFT Likelihood

School of Physical Sciences - Mon, 03/02/2025 - 16:53
Flavour Physics Beyond the Standard Model with the SMEFT Likelihood

New physics beyond the Standard Model (SM) is needed to address open questions within the SM and to explain experimental observations that the SM cannot account for. While direct searches at the Large Hadron Collider have reached their energy limit without finding particles beyond the SM (BSM), precision measurements, in particular those in flavour physics, probe energy scales far beyond the reach of direct searches. In this talk I will discuss how measurements of flavour and other precision observables, combined with Effective Field Theory (EFT) methods, can be used to indirectly search for heavy BSM particles. I will present a likelihood function in the Standard Model EFT (SMEFT) that includes a large number of flavour observables, and show how it can be applied to the flavour phenomenology of BSM models.

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Tue 11 Mar 14:00: Title to be confirmed

School of Physical Sciences - Mon, 03/02/2025 - 12:25
Title to be confirmed

Abstract not available

  • Speaker: Daniel Kious (Bath)
  • Tuesday 11 March 2025, 14:00-15:00
  • Venue: MR12.
  • Series: Probability; organiser: ww295.

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Tue 18 Mar 14:00: Title to be confirmed

School of Physical Sciences - Mon, 03/02/2025 - 12:24
Title to be confirmed

Abstract not available

  • Speaker: Louis-Pierre Arguin (Oxford)
  • Tuesday 18 March 2025, 14:00-15:00
  • Venue: MR12.
  • Series: Probability; organiser: ww295.

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