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SUMMARY:The thermal stability of the holmium single atom magnets in a magn
 etic field
DTSTART:20170428T161500
DTSTAMP:20260427T214919Z
UID:e0fd426b370d43d0bff8fecb57459296032bc5116dd527254fcdb028
CATEGORIES:Conferences - Seminars
DESCRIPTION:Dr. Fabian Natterer\, Laboratory of Nanostructures at Surfaces
 \, Institute of Physics\, EPFL\nThe hallmark of a bar magnet is its stable
  magnetization: North Pole will stay North Pole\, and South\nPole will rem
 ain South Pole. Once we split this magnet\, both halves will also be stabl
 e magnets. As we\ncontinue to break the shrinking magnets into ever smalle
 r and smaller pieces\, we will encounter a\ncritical size at which the pol
 es start to spontaneously fluctuate owing to the onset of quantum\ntunneli
 ng of their magnetization [1]\; the magnets cease to be stable. The critic
 al sizes range from only\na few atoms to hundreds. However\, a recent repo
 rt of magnetic remanence for ensembles of single\nholmium atoms on magnesi
 um oxide [2] provided us with a new perspective of how small a stable\nmag
 net could effectively be and promised a new era of ultra‐dense magnetic 
 data storage. At the\nfundamental limit of a single atom\, however\, the q
 uestion of how to read and write the magnetic\nstates remained. Here we sh
 ow the control of the magnetization of selected Ho atoms by scanning\ntunn
 eling microscopy (STM) [3] using current pulses\, tunnel magnetoresistance
  (TMR)\, and STM\nenabled electron‐spin resonance (ESR) [4]. Below a tun
 neling voltage threshold\, the individual Ho bits\nremain stable for hours
 . We use this stability to build a prototypical two Ho bit atomic memory d
 evice\nto which we write the four possible states and which we read out vi
 a TMR and ESR. We expand our\nunderstanding of the reversal mechanism abov
 e the switching threshold voltage by studying the\nmagnetic field dependen
 ce of the switching rate in magnetic fields of up to 8T and at temperature
 s\nexceeding 40 K [5].\n[1] Gatteschi and Sessoli\, Angew. Chem. Int. Ed. 
 42\, 268 (2003)\n[2] Donati et al.\, Science 352\, 318 (2016)\n[3] Nattere
 r et al.\, Nature 543\, 226 (2017)\n[4] Baumann\, Paul et al.\, Science 35
 0\, 417 (2015)\n[5] Natterer et al.\, in preparation
LOCATION:auditorium CE5
STATUS:CONFIRMED
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