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PRODID:UW-Madison-Physics-Events
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UID:UW-Physics-Event-2308
DTSTART:20120323T203000Z
DURATION:PT1H0M0S
DTSTAMP:20240329T075556Z
LAST-MODIFIED:20120321T184029Z
LOCATION:2241 Chamberlin Hall (coffee at 4:30 pm)
SUMMARY:The quantum and classical properties of spins on surfaces\, Ph
ysics Department Colloquium\, Andreas Heinrich\, IBM Almaden Research
Lab
DESCRIPTION:The scanning tunneling microscope has been an extremely su
ccessful experimental tool because of its atomic-scale spatial resolut
ion. In recent years this has been combined with the use of low temper
atures\, culminating in precise atom manipulation and spectroscopy wit
h microvolt energy resolution. A cluster of magnetic atoms on a surfac
e behaves similar to a classical magnetic particle: itaEuroTMs magneti
zation points along an easy-axis direction in space and magnetization
reversal requires sufficient thermal energy to overcome a barrier. In
this talk we will discuss how many atoms it takes to create such creat
es\, which offers crucial insights into the size limits of stable magn
etic nanoparticles. When the number of atoms becomes too small we obse
rve quantum tunneling of magnetization aEuro"\; in the present cas
e of the aEurooeclassicalaEuro Neel vector. Single atoms that are slig
htly decoupled from conducting substrates behave more like quantum mec
hanical entities. These can be studied with inelastic tunneling spectr
oscopy\, a technique we coined spin-excitation spectroscopy. With this
approach it is possible to measure the energy eigenstates of the quan
tum spin Hamiltonian that describes spins on surfaces with high precis
ion. We will introduce its application to the measurement of the Zeema
n energy\, to magneto-crystalline anisotropy\, and to spin-spin coupli
ng via a superexchange interaction.
\n
\nDr. Andreas Heinrich
Bio
\nAndreas Heinrich leads a research team at IBM's Almaden Rese
arch Center focused on exploring atomic-scale structures for possible
applications in computation and datastorage. In January 2012 Heinrich
and his team presented the worldaEuroTMs smallest magnetic data storag
e elements consisting of only 12 magnetic atoms. The work was publishe
d in the highest ranking scientific journal\, Science\, and widely rep
orted in the media\, including the New York Times. This work was based
on a long-term research effort in HeinrichaEuroTMs team that started
with the exploration of the magnetic properties of individual magnetic
atoms on surfaces over ten years ago\, highlighting IBMaEuroTMs commi
tment to long-term\, exploratory research. Heinrich regularly gives in
vited lectures and seminars\, including plenary lectures at leading in
ternational conferences. His main interest is in the exploration of th
e exciting world of atoms and structures built with atomic-scale preci
sion and in educating the public on the amazing world of nanoscience.
Heinrich is both a scientist and an engineer with a keen interest in a
dvancing the experimental capabilities of state-of-the-art research to
ols. He and his team recently improved the time resolution of scanning
tunneling microscopes aEuro" the mot advanced tool for atomic-scale s
tudies on surfaces aEuro" by a factor of 1 million\, another breakthro
ugh paper published in Science in 2010. HeinrichaEuroTMs longer-term i
nterest lies in the emerging field of quantum computation\, where he h
opes to demonstrate the use of single magnetic atoms on surfaces as qu
bits. Quantum computation has the potential to vastly improve computat
ional performances of computers by taking advantage of the intriguing
world of quantum mechanics that governs the properties of atoms. A nat
ive of Germany\, Heinrich received his PhD in 1998 from the University
of Goettingen in Germany and joined IBM in the same year as a postdoc
in Dr. Donald EigleraEuroTMs team. Eigler is world-renowned for being
the first person to reproducibly move individual atoms on surfaces\,
a tradition carried on proudly in HeinrichaEuroTMs research efforts.
URL:https://www.physics.wisc.edu/events/?id=2308
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