Non-collinear orbital magnetism in molecules, nano-structures and solids

• Applicants: Professor Dr. Helmut Eschrig (†); Professor Dr. Gotthard Seifert
• Subject Area: Physical Chemistry of Solids and Surfaces, Material Characterisation
• Term: from 2003 to 2010
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 5412902

• Final Report Year: 2010

Final Report Abstract

The rapid advance of information technology lead to the development of hard discs with ever higher information storage density in recent years. Up to 100 million pages of text can be stored on a modern pocket-size hard disc with one Terrabit storage capacity, This is the content of a medium-size library. Each bit occupies a hard-disc area of about 1000 nm2 , about the cross sectional area of a small virus. We propose, that certain transition-metal dimers attached to hexagonal carbon rings (e.g., to benzene, to graphene, or to the surface of highly-oriented graphite) can have a potential to be used to built hard discs with up to three orders of magnitude higher storage density than currently available. These devices would operate at low, but technically accessible temperatures. Unsolved problems are (i) corrosion resistance; (ii) deposition of regular arrays and (iii) the read-write process. A press release, http://www.ifw-dresden.de/publications/press/press-releases/magnetische-speicherbits-1000-malkleiner-als-viren, dated December 17, 2009, was considered in two local newspapers (Dresdner Morgenpost, December a 18, 2009, and Sächsische Zeitung, December 21, 2009) and in the German computer journal c’t (No. 4, 2010, pgs. 42 and 43).

Publications

• Full-Potential Local-Orbital Approach to the Electronic Structure of Solids and Molecules, in: Condensed Matter Physics in the Prime of the 21st Century (43rd Karpacz Winter School of Theoretical Physics Ladek Zdrój, Poland, 5-11 February 2007), Ed. J. Jedrzejewski, World Scientific, Singapore 2008, pgs. 271–291. ISBN-13 978-981-270-944-8
  Manuel Richter, Klaus Koepernik and Helmut Eschrig
  
• Transition metal dimers as potential molecular magnets: A challenge to computational chemistry, J. Comp. Chem. 29, 2210–2219, 2008
  Daniel Fritsch, Klaus Koepernik, Manuel Richter, and Helmut Eschrig
  
• Cancellation of spin and orbital moments in URhGe under pressure: a density-functional prediction, Phys. Rev. B 80, 195108 (2009)
  W. Miiller, V.H. Tran, and M. Richter
  
• Co Dimers on Hexagonal Carbon Rings Proposed as Subnanometer Magnetic Storage Bits, Phys. Rev. Lett. 103, 187201 (2009); Virtual Journal of Nanoscale Science & Technology 20, 2009
  R. Xiao, D. Fritsch, M. D. Kuz’min, K. Koepernik, H. Eschrig, M. Richter, K. Vietze, G. Seifert
  
• Ensemble interpretation of L(S)DA+U, Phys. Rev. B 80, 245111 (2009)
  I. Chaplygin
  
• Gd@C82 : Origin of the Antiferromagnetic Coupling between Endohedral Gd and the Free Spin on the Carbon Cage, J. Phys. Chem. C 114, 15 (2010)
  Ali Sebetci and Manuel Richter
  
• Magnetic properties of small Pt-capped Fe, Co and Ni clusters: A density functional theory study, Phys. Rev. B 82, 054418 (2010)
  Sanjubala Sahoo, Alfred Hucht, Markus E. Gruner, Georg Rollmann, Peter Entel, Andrei Postnikov, Jaime Ferrer, Lucas Fernandez-Seivane, Manuel Richter, Daniel Fritsch and Shreekantha Sil