The Effect of Varying Co layer thickness on the Time-Temperature Characteristics of Co/Sb Semimetal Embedded Magnetic Nanoparticles

TL;DR

This study investigates how varying cobalt layer thickness affects the temperature-dependent resistance decay in Co/Sb nanoparticles, revealing a strong correlation and potential for time-temperature sensing applications.

Contribution

It demonstrates the influence of Co thickness on resistance decay times and characterizes the morphological and magnetic changes during aging in embedded nanoparticles.

Findings

Resistance decay time varies fivefold with Co thickness

Decay follows an Arrhenius temperature dependence

Nanoparticles undergo morphological transformations during aging

Abstract

We report the effect of varying cobalt thickness on the temperature-dependent time decay of the electrical resistance of Co/Sb multilayer samples. We find that for a given temperature, a five fold change in the Co thickness produces a 100 fold change in the characteristic decay time of the resistance. We find that the characteristic decay time, as a function of temperature, follows an Arrhenius law. During deposition, the Co evolves single domain magnetic nanoparticles, on the Sb, in either a Volmer-Weber or Stranski-Krastanov growth mode. This metastable state is then encased in 2.5 nm of Sb producing an embedded nanoparticle system. Scanning Tunneling Microscopy (STM) measurements taken before sample aging (annealing at a given temperature for enough time to complete the resistance decay) and after aging show that these nanoparticles undergo morphological transformations during aging. These transformations lead to well defined time dependent decays in both the magnetization and the electrical resistance, making this material an excellent candidate for an electronic time-temperature sensor.