Low Temperature Measurements of Novel Low-Dimensional SystemsJames R. Maloney

James M. Stock

What Are Low Temperatures?Room Temperature 300 KFreezing Point of Water 273 KLiquid Nitrogen 77 KLiquid Helium 4 KOur Sample 1.5 KAbsolute Zero 0 K

So What are Low-Dimensional Systems?1-D Chains

2-D Planes

How Can This Make the World A Better Place?We want better high temperature superconductors

High temperature superconductors have similar characteristics to low-dimensional systems

If were going to make progress, we need to understand these systems!

OutlineI. Reaching Low Temperatures

II. Our Samples

III. Properties Under Investigation

IV. Results

I. Reaching Low TemperaturesDesigned a cell compatible with a cryogenic probe to house our samples

The probe could be chilled by liquid nitrogen, liquid helium, and evaporative cooling

The Sample Cell

The Cryogenic Probe

Bridge Balancing MethodLock-InAmplifierSignalGenerator(Internal)SampleCapacitanceBridge

II. Our Samples(CH3)2NH2CuCl3 MCCL

II. Our SamplesLangmuir-Blodgett (LB) film

III. Properties Under InvestigationSearch for phase transitions of MCCL

By observing capacitance

Look at the conductivity of LB film

Measuring conductance from the capacitance signal

IV. ResultsMCCL

IV. ResultsLB film

IV. ResultsAluminum

What Is Next?Reproducibility of 154 K MCCL transition

Search for second phase transition surrounding 10 K

Investigate possible noise coupling between cavities

Questions?