Sample Holders

Abstract

Abstract Sample holders provide uniform and stable temperature control of the sample; eliminate sample stress due to differential thermal contraction between the sample and holder; minimize noise from induced voltages and magnetic pickup by keeping the effective voltage-tap loop area as small as possible; provide well-designed current and voltage contacts, with enough space between each current contact and the nearest voltage lead to ensure that the current distribution is uniform in the region between the voltage taps; and provide firm mechanical support for the sample, particularly for critical-current measurements where large, magnetic Lorentz forces are a major issue. This chapter considers each of these factors in turn, for both bulk sample holders and thin film sample holders, along with examples and design techniques. It also considers the general nature of four-lead measurements, since this technique determines the overall design of most transport-measurement sample holders.