The NHMFL-Pulsed Magnetic Field Facility at Los Alamos National

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The NHMFL-Pulsed Magnetic Field Facility at Los Alamos National Powered By Docstoc
					The NHMFL-Pulsed Magnetic
 Field Facility at Los Alamos
     National Laboratory

                     C. H. Mielke
               Head of NHMFL-PFF User Program
Technical Area 35

Technical Area 35
            Technical Area 35   Cell 1: 50T 20 ms
                                        50T 300 ms
                                Cell 2: 50T 300 ms
                                Cell 3: 65T 35 ms
                                Cell 4: 65T 35 ms
                                Cell 5: 60T 60 ms
General User Lab 124            Cell 6: test cell
                             Technical Area 35
                     NHMFL Pulsed Magnet Field Profiles

                                                            Capacitor Driven Magnet Profiles

                50                                              50 T Mid Pulse
                                                                60 T millisecond pulse magnet
                                                                65 T User Magnet
Field (tesla)





                  0.0         0.1          0.2            0.3         0.4          0.5          0.6
                                                   Time (seconds)
        New User Bank (NUB)

•Current Bank               •New Bank
  –1.6 MJ                      –4.3 MJ
  –32 mF (4 mF increment)      –33.6 mF (4.2 mF increment)
  –10 kV                       –16 kV
  –128 capacitors              –56 capacitors
  –1 silicon switch            –4 silicon switches
  –6 cell switches             –8 cell switches
  –1 charging supply           –4 charging supplies
                            Will cost $1.2M-$1.6M
                            Will take 12-18 months to build
                            Will enable B>65 T for users
NHMFL-PFF Flagship Programs
60 T controlled waveform system MkII on-line Fall ‗05

                         NHMFL 60T Controlled Waveform Pulses
                                                                100 ms flat top
                                                                Optics pulse (Linear Ramp)
                                                                200 ms flat top
                    50                                          Stepped fields (Specific Heat Experiments)

    Field (tesla)




NHMFL-PFF Flagship Programs
60 T controlled waveform system MkII on-line Fall ‗05
   Ultra-sound transmission
   Specific Heat
   Dilatometry                                60                     60.4
   Magnetization                                                                    Flat Top Expanded View                    NHMFL 60 T LP Magnet
                                                                     60.2                                                        July 20, 1998
   Resistivity                                                                                                                     Shot 241

                                                     Field (tesla)
   GHz & MHz conductivity
   3 w thermal difusivity                     40

                              Field (tesla)                          59.6

                                                                            1.234        1.236      1.238    1.240
                                                                                       Time (seconds)



                                                   0.0                                 0.5                   1.0              1.5           2.0
                                                                                                             Time (seconds)
                    1 msec         Capacitor Bank Tests
                    at 100T
                    peak field     Underway NOW

                     10 msec
                     above 75T

                      2 second
                                  2 MJ Cap Bank for 100T Magnet

Magnetic Field environment
will allow for short pulse like
Future Research Opportunities in
  Pulsed High Magnetic Field
60 T controlled waveform system MkII on-line ‗05
        Ultra-sound transmission
        Specific Heat
        GHz & MHz conductivity
        3 w thermal difusivity

100 T Multi-Shot magnet system on-line Fall ‗06
        MHz Conductivity
        and more…
300 tesla Single Turn Project

                                                                                      2.0            First test shot

                                                               dB/dt signal (volts)
                                                                                                         Single Turn Project First Pulse
                   Open to users in October ‗05                                       1.5                        14 May 2003
                                                                                                                15 kV test shot

                   First Shots will occur in about 2-4 weeks                          1.0

                   Extensive technique development underway
                                                                                            0        1                 2               3   4
                   Funded by LANL LDRD-DR program                                                                    µsec

Containment tank

                              100 ton clamp
                                                                                                300 tesla single turn
                                                                                                apparatus. 3.8 MA
                                                                                                will be generated during
                                                                                                the 6 msec field pulse.

                          60 kV collector plates                                                   Single turn coil
Pulsed field GHz-frequency quantum oscillation measurements.
                          Ross McDonald, Paul Goddard,            (IHRP Funded)
                   Charles Mielke, Neil Harrison, John Singleton.

                                               Tunable to frequency of interest

Organic superconductor k-(BEDT-TTF)2Cu(SCN)2

                                         Well separated resonant modes,
                                         Q-factor ~ 600@300K-1500@4.2K.
GHz-frequency conductivity measurements                 (IHRP Funded)
      of k-(BEDT-TTF)2Cu(SCN)2.               High fields reveal details of
                                              the Fermi-surface topology:
                                              both the a and b-orbits and
                                              stark quantum interference,

           64GHz, 2.1K


  New pulsed field user program capability.
Magnetostriction in pulsed fields

                              gold layer     DV
   5 mm            sample

          plastic capacitance dilatometer

                                             Diagram and picture
                                             of the dilatometer.
                                             Magnetic field is
                                             perpendicular to the
                                             dimension being

      V. F. Correa, C. Mielke ~ NHMFL-LANL
              YbInCu4: 1st order valence transition
          C. D. Immer et al., Phys. Rev. B 57, 71 (1997)

  34.3 T

                                           41.1 K

N. Mushnikov et al., J. Phys.: Condens. Matter 16, 2395 (2004)

                                                                 Magnetostriction in a mid-pulse magnet.
                                                                 The voltage is proportional to the length
                                                                 change. The transition is clearly detected
                                                                 around 36 T.

                        40           80
                             T (K)
                                          V. F. Correa, C. Mielke ~ NHMFL-LANL
Thermal conductivity measurements using 3w technique in high magnetic field

                   D. Kim, F. Balakirev, J. Betts, Albert Migliori
                                                                                           (IHRP Funded)

                                                          Thermal conductivity of Nd0.5Sr0.5MnO3

• 3w technique utilizes a heater
  fabricated on the sample. AC
  current at frequency w excites
  temperature variations at 2w,
  which in turn yields 3w voltage
  signal across the heater itself.




                                                  Kappa (W/mK)

                                                                 3.0                                  196K
                                                                 2.5                                  85K
                                                                 2.0                                  36K


                                                                       0   10   20         30    40   50
                                                                                     Field (T)
Contactless Calorimeter rfAMC: Adaptation of 3-W technique
                                                                            (IHRP Funded)
  T. Coffey, D. Kim, C.H. Mielke
   Thermodynamic measurement
         via contactless conductivity
  Strip heater ---> AM rf coil
  Heater width --> sample width
                                          Fig. 1: Cartoon of thermal penetration from a heater
  Heat diffusion eqn. b>>D               on a semi-infinite metallic sample

  Thermometer--> d in limit d << D
      (dT -> ds -> d)

                                           Fig 2: dc rfAMC Probe.
                                           Choice of vacuum or exchange gas
Technology spinoffs from rfAMC Project
   T. Coffey, C.H. Mielke                                                  (IHRP Funded)

       Plug-N-Play Electronics                 User Friendly Pulsed Field TDO Probe

    Super-heterodyne w/ different bandwidths      Boards available to User Program
    Amplifiers tailored for input to Super-Het    Therm. & pick-up leads integrated
    1st stage of Amp. Integrated onto probe       Minimized cross talk
                                                         --> Gnd Plane
RUS(resonant ultrasound spectroscopy)—resonances of small
           samples yield complete elastic tensor!
 This system is now routinely available for NHMFL users


                                                   2.36 at. % Ga
                                                   310K 7.8 ppm/h
                                                   350K 32ppm/hour





                                               0             60           120   180


                                                             290mK to 400K,
Sign up now for this exciting system!
Field-induced Quantum Critical Point in Cubic CeIn3
dHvA and extraction magnetometry in pulsed magnetic fields

                                                     Fig 2: Fermi surface with
                                                     hot spots of high mass
                                                                                 Fig 3: dHvA oscillations

    Fig. 1: Camparison of the pressure (p) and                                    Fig 4: orientation and
    magnetic field (B) dependent phase diagrams of                                field-dependent mass

 T. Ebihara; Shizuoka U.
 N. Harrison, M. Jaime, J. Lasley; NHMFL - LANL
Charge density wave systems in magnetic fields exceeding the Pauli limit.
                   R.D. McDonald, N. Harrison, J. Singleton, A. Bangura,
                      P.A. Goddard, L. Balicas, A.P. Ramires, X. Chi,

                                                  Fully gapped CDW with finite interchain
                                                  bandwidth such that both Landau quantization
                                                  and the Zeeman splitting contribute to the
                                                  Field dependence of the gap.

Magnetoresistance of CDW system Per2Au(mnt)2
 at fields exceeding the Pauli limit (B > 37T).

                                                   In Per2Pt(mnt)2 the competition between
                                                   localized spin dimerization and the CDW
                                                   formation gives rise to structure in the
 CDW gap closes but remains finite due to          field dependence of the gap.
 formation of a field modulated CDW state.
  High magnetic field as a bulk microscopic probe of the
               martensite phase in AuZn
          P A Goddard, R McDonald, J Singleton, J Lashley.

First ever measurement of de Haas-van Alphen (dHvA)
            oscillations within a martensitic material.
Oscillations measured at 100K - highest temperature dHvA yet
Comparison of data with band-structure calculation indicate
electronic origin for shape memory effect.

                                                                                Typical oscillations

                                                               Fermi surface can be traced across
                                                               the transition, showing evolution of
                                                               martensite phase.

                                                               Co-existence of austenite and
                                                               martensite at low temperature -
                                                               bulk phase separation shown for
                                                               the first time.

                                                               Field dependence of effective
                                                               Dingle temperature reveals
                                                               information on the size of low-
                                                               temperature domains.
       Upper critical field in LiTi2O4
      Evangelia Moschopoulou (UC Davis)
     John Singleton, Paul Goddard (NHMFL)
    LiTi2O4 is an interesting spinel superconductor. But
    what is m0Hc2? Literature values (by extrapolation)
    range from 8-35 T!
    Solution: pulsed-field resistivity at NHMFL-LANL.

                                                           Successful extraction of m0Hc2 versus Tc.
                                                           Alteration of valence increases Hc2 and Tc.
                                                           Hc2 versus Tc is ―BCS-like‖.

•       High-frequency lock-in data (1-10 mA);
•       Fields >33 T needed to separate normal-state
        resistivity from dissipative vortex motion
        (humps, dips) in this granular superconductor.
Hidden order/quantum criticality in U(Ru1-xRhx)2Si2
extraction magnetometry in pulsed magnetic fields and transport in the hybrid

   Fig 1: modification of the phase giagram (suppression of hidden
   order) and robustness of quantum criticality with Rh-doping

     Fig. 2: Nexus between quantum critical point,
     metamagnetic cross-over and transition temperature of
     phase II as a function of Rh doping

 J. Mydosh; Max-Planck
 H. Amitsuka; Hokkaido U.
 N. Harrison, M. Jaime, K.-H. Kim; NHMFL - LANL
Probing quantum criticality in CexLa1-xMIn5
dHvA in pulsed magnetic fields, M = Co, Rh and Ir

      Fig 1: Evolution of the Fermi surface with Ce concentration and
      M: An itinerant 4f Fermi surface is observed only for M = Co
      and Ir for x = 1

      Fig. 2: Ce dependence of the effective masses and mean free paths.
      A shorter mean free path for M = Co and Ir even in the dilute limit
      implies that quantum criticality is determined by differences in
      interactions present in single impurity case

 U. Alver, R. G. Goodrich, I Vekhter, R. T. Macaluso, J. Y. Chan; LSU
 L. Balicas, Z. Fisk, D. Hall; NHMFL - FSU
 N. Harrison, P. G. Pagliuso, N. O. Moreno, J. L. Sarrao; NHMFL - LANL