Magnetic Nanosystems: Making, Measuring, Modeling and Manipulation

Personnel

Project Leader(s):
Ruslan Prozorov

Principal Investigators:
Viatcheslav Dobrovitski, Bruce Harmon, Myron Hupalo, David Johnston, Marshall Luban, Ruslan Prozorov, Michael Tringides, David Vaknin, Jerel Zarestky

Postdoctoral Research Associates:
Kyuil Cho, Wei Tian, Zhihui Wang

Overview

This project is designed to meet the challenge of synthesizing and characterizing new magnetic materials whose basic unit is of nanometer size. This Project will expand the coordinated efforts of recent years in the synthesis and characterization of magnetic molecules so as to target a wider array of nanoscale magnetic systems. Strong collaborative ties with scientists at national and international institutions and facilities enhance the Ames effort. In-house experimental facilities probe spin interactions (when necessary down to millikelvin temperatures) by NMR, fast optics, x-ray, susceptibility, and neutron scattering techniques. This project also includes a strong theory component using analytical methods, classical and quantum simulation tools, and first-principles electronic structure methods.

Subtasks in this project are:

  • Magnetic molecules. An established centerpiece of this entire Project is the study of single crystals composed of nanometer-size magnetic molecules. In future work we will manipulate the synthesis process so as to systematically track the emergence of cooperative, macroscopic magnetic phenomena in 1, 2, and 3 dimensions for a matrix of nano-size building blocks. We will also expand our study of quasi-one-dimensional (1D) and 2D magnets, where the magnetic entities have a nanoscale dimension in two and one dimensions, respectively. The above systems include magnetic geometries leading to spin frustration, a novel state of matter. (M. Luban, Y. Furukawa, D. Johnston, R. Prozorov, V. Dobrovitski, D. Vaknin, J. Zaretsky, B. Harmon). Formal collaborations exist with Paul Koegerler (Jülich) and Christian Schröder (Bielefeld)
  • Single and few spin systems. Investigations of single-spin and few-spin quantum dynamics, in such nanostructures as quantum dots and spin impurity centers in crystals, will help to understand the environmental interactions affecting spin systems and will lead to ways for controlling and suppressing the decoherence of spins in nanostructures. Powerful and accurate numerical techniques, together with modern analytical approaches will be used. Experimentally, fast optical probes will be used to detect and coherently manipulate spin coherence, and assess and control relaxation. Advanced spin resonance techniques will also be employed. (V. Dobrovitski, B. Harmon, Y. Furukawa)
  • Magnetic nanostructures on surfaces. This subtask will use a different approach for self-assembly and the creation of nanoscale spin systems. Magnetic species will be deposited on graphene (for optimal mobility and limited chemical activity), and island formation monitored. Magnetic STM tips will be used to probe the magnetism distribution on the island, and fast probe optical Kerr effects will explore the dynamics. Spin polarized first principles electronic structure calculations will be used to investigate the quantum size effect and magnetic response. (M. Tringides, M. Hupalo, C.-Z. Wang)

Highlights

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Publications

2009
Das S; Kreyssig A; Nandi S; Goldman A I; Johnston D C . 2009. Absence of structural correlations of magnetic defects in the heavy-fermion compound LiV2O4. Physical Review B. 80:104401. abstract
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Matsuo A; Kindo K; Nojiri H; Engelhardt L; Luban M; Brechin E K; Gass I A . 2009. High-field ground-state level crossing and magnetic susceptibility of an {Fe-8}-cubane cluster. Physical Review B. 80:092401. abstract
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Martin C; Engelhardt L; Baker M L; Timco G A; Tuna F; Winpenny R E P; Tregenna-Piggott P L W; Luban M; Prozorov R . 2009. Radio-frequency spectroscopy of the low-energy spectrum of the magnetic molecule Cr12Cu2. Physical Review B. 80:100407. abstract
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Hemmida M; von Nidda H A K; Buttgen N; Loidl A; Alexander L K; Nath R; Mahajan A V; Berger R F; Cava R J; Singh Y; Johnston D C . 2009. Vortex dynamics and frustration in two-dimensional triangular chromium lattices. Physical Review B. 80:054406. abstract
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Hupalo M; Conrad E H; Tringides M C . 2009. Growth mechanism for epitaxial graphene on vicinal 6H-SiC(0001) surfaces: A scanning tunneling microscopy study. Physical Review B. 80:041401. abstract
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Dobrovitski V V; Feiguin A E; Hanson R; Awschalom D D . 2009. Decay of Rabi Oscillations by Dipolar-Coupled Dynamical Spin Environments. Physical Review Letters. 102:237601. abstract
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Fielden J; Kogerler P . 2009. Mn-3(OAc)(6)center dot CH3CN: a porous dehydrated manganese(II) acetate. Acta Crystallographica Section C-Crystal Structure Communications. 65:M224-M227. abstract
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Singh Y; Lee Y; Harmon B N; Johnston D C . 2009. Unusual magnetic, thermal, and transport behavior of single-crystalline EuRh2As2. Physical Review B. 79:220401. abstract
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Pieper O; Lake B; Daoud-Aladine A; Reehuis M; Prokes K; Klemke B; Kiefer K; Yan J Q; Niazi A; Johnston D C; Honecker A . 2009. Magnetic structure and interactions in the quasi-one-dimensional antiferromagnet CaV2O4. Physical Review B. 79:180409. abstract
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Niazi A; Bud'ko S L; Schlagel D L; Yan J Q; Lograsso T A; Kreyssig A; Das S; Nandi S; Goldman A I; Honecker A; McCallum R W; Reehuis M; Pieper O; Lake B; Johnston D C . 2009. Single-crystal growth, crystallography, magnetic susceptibility, heat capacity, and thermal expansion of the antiferromagnetic S=1 chain compound CaV2O4. Physical Review B. 79:104432. abstract
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