Status and Highlights of the Pulsed Field User Program

1. 2nd run cycle for the 85T MS magnet user program. 85T MS magnet call for proposals was 100% oversubscribed. The 1st run cycle was completed in January 2010. • Installation of the PFF’s first helium reliquifier completed in the late spring reduced the LHe consumption of this well used magnet by approximately 80%. Status and Highlights of the Pulsed Field User Program Recent high-magnetic-field experiments on the "High Tc" cuprates; Fermi-surface instabilities as a driver for superconductivity; John Singleton, Ross McDonald and Susan Cox, PhysicaB: Physics of Condensed Matter 404, 350-353 (2009)  Exact mapping of the dx2-y2 Cooper-pair wavefunction onto the spin fluctuations in cuprates: the Fermi surface as a driver for 'high Tc' superconductivity; Ross D. McDonald, Neil Harrison, and John Singleton, J. Phys.: Condens. Matter,21,012201 (2009) Nearly isotropic superconductivity in (Ba,K)Fe2As2 H.Q. Yuan, J. Singleton, F. F. Balakirev, S. A. Baily, G. F. Chen, J. L. Luo & N. L. Wang NATURE, 457,565 (2009) as of summer 2010, mid-point in current award period

2. 100 Tesla Science* MPA-NHMFL Los Alamos National Laboratory *Supported by DOE’s Office of Basic Energy Sciences Quantum Oscillations in the Underdoped Cuprate YBa2Cu4O8 E. A. Yelland, J. Singleton, C. H. Mielke, N. Harrison, F. F. Balakirev, B. Dabrowski, and J. R. Cooper PRL 100, 047003 (2008) Fractalization drives crystalline states in a frustrated spin system Suchitra E. Sebastian, N. Harrison, P. Sengupta, C. D. Batista, S. Francoual, E. Palm, T. Murphy, N. Marcanoa, H. A. Dabkowskae, and B. D. Gaulin PNAS 105, 20157 (2008) Nearly isotropic superconductivity in (Ba,K)Fe2As2 H. Q. Yuan1, J. Singleton, F. F. Balakirev, S. A. Baily, G. F. Chen, J. L. Luo & N. L. Wang NATURE, 457,565 (2009) Observation of quantum oscillations in an underdoped cuprate superconductor using a tunnel-diode oscillator technique in pulsed magnetic fields up to 85 T. There is a clear signal, periodic in inverse field and possible evidence for the presence of two components of slightly different frequency. The quasiparticle mass was determined and in conjunction with the results of Doiron-Leyraud et al. the present measurements suggest that Fermi surface pockets are a general feature of underdoped copper oxide planes. Resistivity measurements of superconductivity in iron-arsenic-based compounds with a superconducting transition temperature (Tc) as high as 56 K shows that (Ba,K)Fe2As2 in a magnetic field up to 60 T is in fact quite isotropic. Such behavior is strikingly different from all previously known layered superconductors, and indicates that reduced dimensionality in these compounds is not a prerequisite for ‘high-temperature’ superconductivity The fractalized Hofstadter butterfly energy spectrum predicted for magnetically confined fermions diffracted by a crystal lattice has remained beyond the reach of laboratory-accessible magnetic fields until now. The investigators find SrCu2(BO3)2, a geometrically frustrated spin system, to provide a sterling demonstration of a system in which bosons confined by a magnetic and lattice potential mimic the behavior of fermions in the extreme quantum limit.

3. 100T MS program operating a solid user program with shots at 100T. • 300T single shot magnet fully integrated into the user program with an additional dedicated staff scientist and technician. • Fully operational LHe and LN2 recovery and re-liquifaction facility at the NHMFL-PFF to make us fully cryogen self sufficient . Visionfor the Pulsed Field User Program as of summer 2010, mid-point in current award period