Submicron structures 26th January 2004 msc

Condensed Matter Physics

Photolithography to ~1 μmUsed for...

Spin injection Flux line dynamics Josephson junctions SQUIDs Superconducting mesa

structuresfeaturesto 1-2 μm

Device Physics cleanroom

Submicron structures 26th January 2004 msc

Condensed Matter Physics

Opportunities below 1 μm

Higher interface resistance R simplifies interpretation. Get R > h/e2 : resistance quantum

Measure spin flip length < 1 μm

Isolate individual crystal grains/twins: directions important for d-wave superconductors

Access mesoscopic quantum behaviour: single electron, single spin, single Cooper pair

d d

300 nm

I

Submicron structures 26th January 2004 msc

Condensed Matter Physics

Focused Ion Beam fabrication

30 kV Gaion source

Focus to ~30 nm.Remove or addmaterial

Observe by SEM while writing,

select desired region of sample

University Nanotechnology Research Centre(Mechanical Engineering)

Submicron structures 26th January 2004 msc

Condensed Matter Physics

Superconducting wires to 100 nm (so far...) by FIB

Well-controlled structure

Quantum effects easily seen

6 μm photolith.270 nm FIB

Superconducting phase slip

Submicron structures 26th January 2004 msc

Condensed Matter Physics

Physics << 1 μm

Use quantum effects as a probe of electron systems – e.g. Coulomb blockade to measure energy distribution

Quantum computers motivate study of systems having quantum coherence

Combine mesoscopic conductors with intrinsic Josephson tunnelling

Submicron structures 26th January 2004 msc

Condensed Matter Physics

Our strengths

Expertise in ultrasensitive electrical measurements: - Shot noise - SQUID detectors

Well-equipped for quantum-dominated measurements: - mK temperatures - 10 T fields

Wide range of interesting material properties - HTc have energy gap > kT & charging energy - HTS have nm-scale laminar structure - Ferromagnetic, unconventional materials available

Submicron structures 26th January 2004 msc

Condensed Matter Physics