Skip to Content.
Sympa Menu

fizinfo - [Fizinfo] Emlékeztető/Reminder: Ortvay kollokvium/Ortvay colloquium ma/today

fizinfo AT lists.kfki.hu

Subject: ELFT HÍRADÓ

List archive

[Fizinfo] Emlékeztető/Reminder: Ortvay kollokvium/Ortvay colloquium ma/today


Chronological Thread 
  • From: Kormányos Andor <andor.kormanyos AT ttk.elte.hu>
  • To: "fizinfo AT lists.kfki.hu" <fizinfo AT lists.kfki.hu>, "ttk-fiz-faculty AT listbox.elte.hu" <ttk-fiz-faculty AT listbox.elte.hu>, "ttk-fiz-kutato AT listbox.elte.hu" <ttk-fiz-kutato AT listbox.elte.hu>, "ttk-fiz-emeritus AT listbox.elte.hu" <ttk-fiz-emeritus AT listbox.elte.hu>, "ttk-fiz-postdoc AT listbox.elte.hu" <ttk-fiz-postdoc AT listbox.elte.hu>, "ttk-fiz-phd-hallgatok AT listbox.elte.hu" <ttk-fiz-phd-hallgatok AT listbox.elte.hu>, "ttk-fiz-alkalmazottak AT listbox.elte.hu" <ttk-fiz-alkalmazottak AT listbox.elte.hu>
  • Subject: [Fizinfo] Emlékeztető/Reminder: Ortvay kollokvium/Ortvay colloquium ma/today
  • Date: Thu, 9 Nov 2023 08:29:16 +0000
  • Accept-language: hu-HU, en-US
  • Arc-authentication-results: i=1; mx.microsoft.com 1; spf=pass smtp.mailfrom=ttk.elte.hu; dmarc=pass action=none header.from=ttk.elte.hu; dkim=pass header.d=ttk.elte.hu; arc=none
  • Arc-message-signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=microsoft.com; s=arcselector9901; h=From:Date:Subject:Message-ID:Content-Type:MIME-Version:X-MS-Exchange-AntiSpam-MessageData-ChunkCount:X-MS-Exchange-AntiSpam-MessageData-0:X-MS-Exchange-AntiSpam-MessageData-1; bh=wSVyLkqh3DvL0FjswRL6v87Pp3zx8K9tT8K3TKphAGo=; b=B/ffUH8H/NzYgHbl5+GMpXJd86obX8F4WrobobAO8YyHNpbh+Oirru6k3IzxAEo/J3Klyg8xXmyFy2ZeKPowlUD7xmGgIT9yvq0u6//sE3FVRNPv+auXgdHvG3VLV07SwZD65OXot6cQR1K89Ai2E0Y8nEnGykV8SAR7n8eE3E/3gR+oZ+x+Xb/7geW1m0kLJALxW1Qq4W3tbdhSqTnh30ZE2YfzanXgNHE8pXdD4hRqRDIAQHpfp8QYlYM6Zx/vjMqEczXAM7FBiukclQKphRYi/6imL+doSmxRiXqNTB3A53VmLdzNbobnor8GLajHrh6yxLHHAm8dZtWQXvTUGA==
  • Arc-seal: i=1; a=rsa-sha256; s=arcselector9901; d=microsoft.com; cv=none; b=QLSsr7AVKTqOQ5z8xtZ2iUt5lIi6qqRS4G6nSP7+pjR0kbNWipuZ3hhWSUYnyPmWDgjjdm3//XufN1Nc3kV90wt1eXGBDbNULXg1tSe1n5Dsf+7QcfEX1U6J4usw/ZId6H8hfTKjBMVJQuaBPypT0SraWflNyLyMsh+ct8OpehV0Gs6faFoizY5HuPN04SUdB00zCxgHF3kyWwPiWWwHcjY+JGQU9bm4BuX1pS1rrTm5ZlqqRKvPusvOt3TqT678KcSLFdwsQAbZDOjUgBFL32vfw1W0VglESFmehtfxY04mHRII5FfJFiPTsKlCxWhfQ8LjlyCDoN9IM3LM90PBNg==
  • Authentication-results: smtp012.wigner.hu (amavisd-new); dkim=pass (1024-bit key) header.d=eltehu.onmicrosoft.com
  • Authentication-results: dkim=none (message not signed) header.d=none;dmarc=none action=none header.from=ttk.elte.hu;

ELTE TTK Fizikai Intézet / ELTE Institute of Physics


ORTVAY KOLLOKVIUM / ORTVAY COLLOQUIUM
(https://physics.elte.hu/ortvayseminar)


Thursday, 9th November 2023, 15:00h.

Pócza Jenő Classroom, Physics Building 1.71

Pázmány Péter sétány 1/A, 1117 Budapest.


Balázs Újfalussy

Wigner Research Center for Physics

Shiba bands, topology and Majorana Zero Modes in artificial spin chains from
first principles

Majorana-zero-modes (MZMs) were predicted to exist long ago as edge states of
some particular physical systems. MZMs have become an important topic because
of their potential applications in topological quantum computing, and simply
because of the interest that they should host quasiparticles that are their
own antiparticles. Despite the lot of buzz triggered by their possible
applications as quantum bits with topological protection against decoherence,
experimentally it is still very challenging to uniquely identify MZMs based
solely on the spectral properties. At the same time, most theoretical models
which claim to calculate Majoranas are forced to use entirely unrealistic
parameter sets. Usually, in such situations, first-principles calculations
are especially helpful, both in identifying and in designing such topological
systems.

Here we apply a new formalism to study MZMs from first principles
calculations in the superconducting state by solving the Dirac-Bogoliubov-de
Gennes equations via band theoretical methods. Such an approach has the
advantage that magnetism, superconductivity, and relativity is handled on the
same footing in a material specific way, while the special geometry of the
system can also be included.

In the talk, after a short study of single impurities as an introduction to
the method, we will look at chains of magnetic atoms deposited on the surface
of a superconductor. More specifically we will concentrate on a particular
system considered prototypical: an Fe chain on the top of Au-covered Nb(110)
surface, mostly because this system attracted significant experimental
interest over the past two years. I will show that ferromagnetic chains do
not support an MZM in this system, however, a broad range of spin-spirals can
be identified with a robust zero energy state displaying all signatures of
MZMs. We explore the formation and distinction of topologically trivial and
non-trivial zero energy edge states, their stability against changes in the
direction and magnitude of the local exchange field. Furthermore, we also
discover from first-principles that the topological edge states form an
exotic type of state: an internally antisymmetric triplet. Through various
computational experiments I will demonstrate the emergence of the phenomena
called topological fragmentation and show how Majorana Zero Modes can be
shifted within the chain, as a first step towards the design and
implementation of a braiding protocol.


Andor Kormányos
coordinator

















Archive powered by MHonArc 2.6.19+.

Top of Page