Condensed Matter Experiment

FacultyRobert Anderson, ProfessorS. M. Bhagat, Professor Dennis Drew, ProfessorEllen Williams, ProfessorMichael Fuhrer (with CSR), Assistant ProfessorMin Ouyang, Assistant ProfessorRobert Park, Professor (APS – “What’s New”)Richard Webb, Professor (with CSR) (on leave)

Affiliated Faculty (LPS)D. Romero B. KaneK. SchwabB. Barker

Condensed Matter Experiment

FacultyRobert Anderson, Professor RS. M. Bhagat, Professor TDennis Drew, Professor REllen Williams, Professor RMichael Fuhrer (with CSR), Assistant Professor (Hired 1999)Min Ouyang, Assistant Professor (Hired 2004)Robert Park, Professor (APS – “What’s New”)Richard Webb, Professor (with CSR) (on leave)

Affiliated Faculty (LPS)D. Romero B. KaneK. SchwabB. Barker

Condensed Matter Experiment

3 March 2005

Post-docs 12 (+3 LPS) RGAs 22 (+12 LPS) Undergrads 4 (+1 LPS) Research Scientists 4 visitors (> 1 month) 2 Publications (2000-2005) 108 Invited talks (2000-2005) 99 Present Annual Funding $3,412,050 Funding Sources NSF-MRSEC, NSF-NIRT

NSF, ARL, ARO, NSA NIST, NRL, DOE, CSR Northrop-Grumman

US News ranking: 10

OutlineQuantum properties at the nanoscale to mesoscale

(CME, CSR, LPS; Anderson, Drew, Lobb, Wellstood, Webb, Ouyang, Fuhrer, Kane, Schwab, Barker)

Applied Statistical Mechanics: properties at the nanoscale(CME, IPST; Williams, Weeks, Das Sarma, Einstein)

Low-Dimensional Interfaces: Organic and Inorganic materials, molecular electronics (CME, Chemistry; Fuhrer, Lee, Reutt-Robey, DeShong, Ouyang, Sita, Williams)

Nanophysics: Nanoscale imaging, devices, assembly (CME, EE, Materials, LPS; Drew, Fuhrer, Gomez, Lee, Phaneuf, Williams)

Magnetic Oxides: Dilute magnetic oxides, multiferroics and high TC superconductivity(CME, CSR, Materials, NIST, Rutgers); Bhagat, Drew, Greene, Ogale, Takeuchi, Venkatesen, Lynn, Cheong)

Maryland Infrastructure• NSF-Materials Research Science and Engineering

Center Interdisciplinary, competitively funded research center,

Collaborative research programs; Shared Experimental Facilities, Educational and Industrial Outreach Programs. Director: Ellen Williams

• Center for Superconductivity Research Established as a state-supported research laboratory in 1988.

Director, Prof. R. Greene. • Institute for Physical Science and Technology

State-supported interdisciplinary research institute. Strengths in non-linear dynamics, statistical mechanics, applied mathematics, space physics. Director, R. Roy.

• Maryland Center for Integrated Nano-Science and Engineering/ Kim Building

State-supported research center to for research and applications of nanotechnology. Director: G. Rubloff

• Laboratory for Ion Beam Research and Applications Focused Ion Beam research and application

• Laboratory for Physical Science Neighboring DoD Laboratory with 20+ year history of support

for condensed Matter Physics at UMD. Director: Bernadette Preston

History: UMD Nanotechnology FlagshipPhysics Liaison - E. Williams (1998-present) + M. Fuhrer (2004-present)

• 1998: Chair- Steve Wallace, Acting Dean - John Osborne Proposal in parallel with Engineering proposal. Requested infrastructure support + 2

faculty hires Result - Michael Fuhrer recruited in 1999

• 1999: Chair - Jordan Goodman, Dean - Steve Halperin Proposal submitted by Engineering with one hire in Physics endorsed by CMPS Result – not approved

• November 2000: Chair - Jordan Goodman, Dean - Steve Halperin endorse proposal for three Nanotechnology hires in CMPS to be included in joint Engineering/CMPS Initiative. Search is initiated, then cancelled by the Dean.

• Fall 2003: University provides a new line in physics to be used for a nanoscience hire

Result: Min Ouyang hired in 2004• 2003-2004 IPST undertaking facilities renovation in preparation for two

experimental biophysics hires. Candidates selected in biophysics search (chair: E. Williams) to be presented to Physics faculty March 10.

• 2004 Dean of Engineering - Nariman Farvardin proposes a major initiative in Nanoscience/Nanotechnology to be coordinated through IREAP in conjunction with new Nanofabrication facility in Kim Bldg. P. O’Shea appointed director of Nanoscience and G. Rubloff director of M-CINSE (Maryland Center for Integrated Nanoscience and Engineering).

http://www.physics.umd.edu/cal/spevents/nanoscience/index.html

Nanophysics & Devices:LPS Program Overview

H.D. Drew, M.S. Fuhrer, S.B. Lee, J. Melngailis, R.J. Phaneuf, E.D. Williams, M. Zachariah

Collaborations: P. Abshire, R. Ghodssi, R. Gomez, E. Smela, D. Romero, G. Rubloff

• Program focus: Develop and evaluate advanced nano-optical and nano-electronic technologies for sensing and information processing. Nano-electronics with carbon nanotubes and innovative nanotube

materials (Fuhrer, Lee, Melngailis) Nanoparticle-enhanced fluorescence for sensing applications

(Phaneuf, Zachariah, Drew) Integration of nano-electronics with organic electronics and

photocells, etc. onto flexible plastic substrates (Williams) Nanoscale optical sensing and nano-antennas (Drew)

Fuhrer Group - Electronic Properties Fuhrer Group - Electronic Properties of Carbon Nanotubes of Carbon Nanotubes

1 10104

105

(c

m2 /V

s)

Vth - V

g (V)

50 K 100 K 150 K 200 K 250 K 300 K

Ultra-long nanotubes:• Charge carrier mobility (highest of any semiconductor at RT)• Saturation velocity

Nanotube transistors: • Single-electron detection and memory• High-frequency devices

Novel Imaging/Fabrication Techniques:• Scanning-Probe microscopies of transport

Collaborations:• John Melngailis (ECE) – electron microscopy, electron-beam deposition of metal contacts• Gary Rubloff (Materials) – ALD of metals, high-k dielectrics on nanotubes

Funding: NSF, Army Research Lab, Northrop-Grumman T. Dürkop, et al., Nano Letters 4, 2004

Fuhrer Group - Molecular ElectronicsFuhrer Group - Molecular Electronics• Single-molecule measurements in electromigration-fabricated break junctions• First observation of expected signatures of resonant conduction through a single molecular state: Lorentzian resonance with conductance ~G0.

Collaboration with Larry Sita (Chemistry), Harold Baranger, Weitao Yang (Duke University)

Funding: NSF, DOE

-100 -50 0 50 1000.0

0.2

0.4

0.6 Experiment

G (

GO =

2e2 /h

)

V (mV)

2-Lorentzian fit

S. A. Getty, et al., (submitted to PRL)http://xxx.lanl.gov/abs/cond-mat/0409433

Fuhrer Group - Other Research Fuhrer Group - Other Research

“Nanopatches”: Two-dimensional crystals of layered transition-metal dichalcogenides

Collaboration with Ellen Williams (Physics)Funding: NSF

Thin-film electronics with nanostructured organic materials or carbon nanotube films

Collaboration with Ellen Williams (Physics), Sang Bok Lee (Chemistry), Romel Gomez (ECE)Funding: LPS Au

Au

Nanotube film bare

SiO2

TaS2 Nanopatch with gold electrodes

Nanotube Thin-Film Transistor

Laboratory for NanoSpintronicsPI: Min Ouyang

(http://www2.physics.umd.edu/~mouyang/)

Research Interest:(1) Development of novel synthetic methodologies for low dimensional

spin-based hybrid organic-inorganic nanostructures.

NW-NT heterojunction

Nature 399, 48 (1999) Carbon SWNT

Science 292, 650 (2001) CdSe Quantum Dots

Science 301, 580 (2003)

5nm1nm50nm

(2) Investigation of fundamental basis for spin-charge interactions and spin transport within nanostructured systems with new experimental techniques such as femtosecond optical spectroscopy, magnetotransport and low temperature scanning probe microscopy.

Time resolved Faraday rotation spectroscopy for investigating spin dependent physics in nanostructures

Science 301, 580 (2003)

Williams group - statistical mechanics Williams group - statistical mechanics of surface structuresof surface structures

Application of direct imaging techniques to determine structural distributions:

• equilibrium statistical mechanics•Step free energies•Fluctuation time constants•Size-dependent crossover

Nanostructure Evolution: • Predictive evolution based on step unit • Driven Instabilities and patterning

Stochastic “predictability”:• Demonstration of first passage phenomena

Collaborations:• Theory: Einstein, Weeks, DasSarma

Funding: NSF, DOE

Williams Group - Electromigration and NoiseWilliams Group - Electromigration and Noise

Fundamental issues of diffusional bias due to

electron scattering from internal surfaces • pattern formation - kinetic instabilities• direct observations of fluctuation bias

Instrumental/Materials applications: • Development of MFM to observe current crowding directly•Development of UHV nanowire fabrication

Correlation of electron transport noise with atomic scale structure

Collaborations:• Theory: Philip Rous, UMBC•Experiment: M. Fuhrer, S.B. Lee (Chemistry

Funding: NSF, DOE

Williams group - organic electronics Williams group - organic electronics

Investigation of interface effects as scale thickness and lateral scale of organic device structures

•Organic MBE•Nano-transfer print lithography

Thin-film electronics with nanostructured organic materials or carbon nanotube films

Collaboration with M. Fuhrer (Physics), Janice Reutt-Robey, Sang Bok Lee and Phil DeShong (Chemistry), Danilo Romero (ECE)Funding: LPS

1.6 1.8 2 2.2 2.4 2.6 2.8

10 100

368

372

376ZnCr

2O

4

0 (c

m-1)

Temperature (K)

The magnetic frustration of Cr ions in corner sharing tetrahedra (the pyrochlore lattice) have leads to a Neel temperature of 12 K despite a Curie-Weise temperature of 390 K. The frustration is broken by a Peierls distortion of the lattice at TN and a triply degenerate IR phonon splits into a singlet and doublet. Softening of the phonon above TN probe spin correlations in the spin liquid state. Sushkov et al., PRL accepted

Drew Group: Oxide Magnetism

Probing spin correlations with IR phonons in the strongly frustrated magnet ZnCr2O4

Collaborations: MRSEC, CSR, Materials, Cheong (Rutgers), Lynn (NIST).Funding: NSF MRSEC

Drew Group: High TC Superconductivity

1H H

H i

ARPES: Nd2-xCexCuO4

Armitage, et al.,PRL 87, (2001).

Rapid growth of H observed in pseudogap state is signature of Fermi pockets. Stripes, “arcs”, Mott transition and other models lead to reduction of H

Fermi pockets in underdoped YBa2Cu3O6+x deduced from measurements of the Hall effect in the infrared.

L. Rigal et al., PRL 93 (2004).

Collaborations: Greene (CSR), Gu (Brookhaven), Millis (Columbia). Funding: NSF

20 40 60 80 100 120 140 1601E-8

1E-7

1E-6

1E-5

1E-4

1E-3

0.01

0.1

1

Far Field Throughput of NSOM Probes

Th

rou

gh

pu

t

Minor Axis of Aperture (nm)

Etched tip Etched tip Pulled tipE

E

E

20 40 60 80 100 120 140 1601E-8

1E-7

1E-6

1E-5

1E-4

1E-3

0.01

0.1

1

Far Field Throughput of NSOM Probes

Th

rou

gh

pu

t

Minor Axis of Aperture (nm)

Etched tip Etched tip Pulled tipE

E

E

E

E

E

Drew Group: Nano-optics High optical throughput NSOM probes have been realized using etched polarization preserving fiber.

Applications: florescence imaging, quantum dot spectroscopy, direct writing superconducting circuits.

Collaborations: LPS, Materials, Williams, Phaneuf. Funding: LPS

Diluted Magnetic SemiconductorsA1-xMxB

Examples: Hg1-xMnxTe, Pb1-xGdxTe, Ga1-xMnxAsProperties: 1. Electronic properties influence magnetic

properties and vice versa. 2. Large negative magnetoresistance.

3. Controllable bandgaps.Applications: 1. Frequency tunable IR detectors.

2. Avalanche photodiode detectors. 3. Thermoelectric components. 4. Magnetic field detectors.

Research Projects: 1. Magnetic contribution to heat capacity. Probe of exchange interactions.

2. MBE-prepared thermoelectric materials.

3. Magnetically tunable IR detectors.Collaborations: Institute of Physics (Warsaw), CSR, LPS,

Notre Dame, UMES, Howard U.

Anderson group

Quantum Computing*

Josephson Junction Qubits

Rabi Oscillations in an LJ isolated junction

0 10 20 300.0

0.2

0.4

0.6

Time (ns)

P1

LJJJ-Nb

7.6 GHz

|0>|1>

Coherence time:T2

' ~10 ns ~ 1/1

7.6 GHz Microwaves switched on at t=0 when resonant with 0->1 transition

1o

•Present Research: Microwave spectroscopy in coupled Josephson

junctions. Investigation of escape rates, isolation schemes and variable

coupling approaches. Examine gate operations. Prepare 10-qubit chips.•Collaborators: CSR, Wellstood, Lobb, Dragt•Funding: LPS

Bhagat Group

Ferromagnetic Resonance has been the main focus of the Bhagat group. We began work with single crystals (pure metals & alloys), branched into amorphous alloys (metglasses) and disordered FM’s (…etc), perovskite manganites, Garnets, orthoferrites, and most recently we are concentrating in microwires and nanostructural materials- powders, thin films, multi-layers.

Collaborations: groups in Russia and Spain, S. Lofland (Rowan University) and S. Tyagi (Drexel).

Condensed Matter at Laboratory for Physical Sciences

Bruce Kane (Visiting Associate Research Scientist

Semiconductor base quantum computer

Keith Schwab (Adjunct Assistant Professor)

Superconductor based quantum computer, Low temperature physics

Barry Barker

low temperature STM

SET Array for QCBruce Kane, LPS

• Array of Al SETs separately addressable using scanned probe

• Randomly doped Si substrate: weak localization measurement of P -doped layer to measure dopant segregation and diffusion

• Application: Spin Quantum Computing in Si

Quantum Properties at the Nanoscale

• Quantum Limits of Motion in Nanomechanics – K. Schwab - LPS

• Demonstrate the quantum behavior of a nanomechanical oscillator at 10mK temperatures.

• Show the effects of the uncertainty principle, quantized energy, and the existence of superposition

• Nanoscale Landscape of Semiconductor Dopants – B.I. Barker - LPS

• Probe spatial extent, spectroscopic features and Zeeman splitting of dopants in semiconductors

• Develop Very-Low Temperature STM for spectroscopic measurment of Zeeeman splitting - test Te/GaAsy.)

rf SET10 MHZ resonator

Condensed Matter Experiment• Limiting Issues

Quality/Quantity of space issues Area and quality of laboratory space and space for equipment

storage, poor AC and electrical power. Office space for Post-docs, Grad students Poor facilities support: no clear administrative process to

initiate laboratory modifications, no recognizable tracking system once process is initiated, PIs waste huge amounts of time dealing with even trivial facilities issues that will be fully paid by grants. Research activities can be delayed for years. Major efforts by outstanding Associate Chair cannot solve problem.

Bureaucratic Hurdles University safety officials are helpful within their limits, but

unaware of state-of-the art approaches to safe laboratory practices. Individual faculty member must research any new safety issue on his/her own time, and then spend large effort to convince safety staff that modern approaches are viable. (And then deal with facilities…)

…continued

Condensed Matter Experiment• Limiting Issues

Bureaucratic Hurdles (continued) Limited U. support for activities required/encouraged by funding

agencies: educational outreach, industrial outreach, recruiting and supporting diverse population of graduate students, outreach to developing countries

Research scientist ranks in CMPS barred to laboratory managers even where Ph.D. level expertise is required

Repetitive wasteful paperwork/reporting burdens Research Environment/Intellectual Environment

U. administration slow to recognize (and support faculty in responding to) national science initiatives and directions (e.g. nanoscience, advent of DHS…). Administratively determined priorities and plans poorly communicated to faculty.

Multiplication of initiatives, centers, etc. fragments intellectual community. Specific to CM - need to coordinate Biophysics, Nanoscience in CM, IREAP, MCINSE efforts to consolidate intellectual community