RT Dissertation/Thesis
T1 Thermomagnetic properties at the nanoscale
A1 Serantes Abalo, David
AB This Thesis deals with the magnetic properties and magnetocaloric effect (MCE) in the single-domainrange. The motivation to carry out such work is based on the unusual magnetic properties that commonmaterials exhibit in nanoscaled dimensions when they reach the single-domain size, often radicallydifferent and/or enhanced with respect to their bulk counterparts. These new properties have a widerange of technological applications, ranging from magnetic recording to biomedicine. In particular, thestudy of the MCE in these low-dimensional systems is of primordial importance both for refrigerationpurposes of micro- and nano-electro mechanical systems, and for biomedical applications as magneticagents for hyperthermia treatments.Characterizing the magnetic properties (and the MCE) in these reduced dimensions is very complex,since the magnetic response of the system is strongly dependent in several factors as size, shape,anisotropy, dipole-dipole interaction, etc, which make difficult to control the parameters ruling its behaviour,and consequently, limit their technological use. Furthermore, single-domain magnetic systemsmay exhibit superparamagnetic (SPM) behaviour depending on the specific conditions (applied magneticfield, temperature, magnetic anisotropy, size, shape, etc). SPM behaviour is the paramagnetic-liketemperature dependence that single domain magnetic entities may exhibit at certain conditions, and itis evident that needs to be perfectly controlled depending on the specific applications we are interestedin (for example, for magnetic recording purposes it is necessary to avoid SPM fluctuations, so that themagnetic information remains stable against thermal fluctuations).In this context, the use of a computational technique (Monte Carlo one in our case) arises as avery useful tool to study such magnetic nanostructures: on the one hand, with a MC method thecharacteristics of the system are perfectly controlled and, on the other hand, we can study problemswith no analytical solution, as for example the magnetic dipole-dipole interaction. This is the mainobjective of the present work: with the help of a MC technique we can study different nanostructuredsystems, as randomly distributed nanoparticles systems or chain-like nanoparticle assemblies, and toinvestigate how the different parameter (magnetic anisotropy, size, shape, interparticle interactions,etc) rule its behaviour. This knowledge will then be applied to search for the optimizing MCE-basedapplications both for hyperthermia and refrigeration purposes.
SN 978-84-9887-765-6
YR 2012
FD 2012-02-02
LK http://hdl.handle.net/10347/3616
UL http://hdl.handle.net/10347/3616
LA eng
DS Minerva
RD 23 abr 2026