Nanoparticle magnetization measurements by a high sensitive nano-superconducting quantum interference device

Abstract

A high sensitive nano superconducting quantum interference device (nanoSQUID) operating as a magnetic flux to critical current transducer with a suitable feedback circuit is employed to measure the magnetization of ferrimagnetic iron oxide nanoparticles. An improved SQUID responsivity has been obtained by using a loop inductance asymmetry. Iron oxide nanoparticles having a mean diameter of 8 nm have been excited by applying a polarizing field in the plane of the nanoSQUID loop. The field dependence of the nanoparticle magnetization at T = 4.2 K shows magnetic hysteresis. Magnetic relaxation measurements are reported and compared with those obtained by using a commercial measurement system

Superconducting quantum interference device without Josephson junctions

“…A fundamentally new suggestion of this work, as compared to the previous ones, is the use of asymmetric link-up of current leads. Asymmetric connection to the interferometer with two Dayem bridges was implemented in recent work [7]. A new point as compared to [7] is the use of a sharp change in the average value of the critical current under a change in the quantum number near Φ = (n + 0.5)Φ 0 .…”

Nanobridge superconducting quantum interference devices: Beyond the Josephson limit

“…Limits of the model I have shown that using the model presented here, which does not take the Josephson effect in NB-electrode joints into account, I cs (Φ a ) of NBSs is derivable. The result is triangular-shaped I cs (Φ a ) with one to two branches, as has been observed in several experiments [15,20,21,[35][36][37][38][39][40][41][42][43][44][45]. Now, let me discuss the limits in which the model works.…”

Sample Preparation for Inorganic Trace Element Analysis

“…At this point the current is switched off, and I c is calculated from the duration of the ramp 38 . This technique can also be used with a FLL scheme [38][39][40] . Sensitivity is limited by the accuracy in determining I c , which is described by the escape of a particle from a potential minimum.…”