Anomalous low-temperature magnetoresistance dips in sputtered ferromagnetic thin films and multilayers

Journal Article · Tue Apr 01 00:00:00 EDT 2008 · Journal of Applied Physics

DOI:https://doi.org/10.1063/1.2901185· OSTI ID:21137285

Allia, Paolo ^[1]; Celegato, Federica; Coiesson, Marco; Tiberto, Paola; Vinai, Franco ^[2]; Albertini, Franca; Casoli, Francesca ^[3]

---

1. Dipartimento di Fisica, Politecnico di Torino, Corso Duca degli Abruzzi 24, I-10129 Torino (Italy)
2. INRIM, Strada delle Cacce 91, I-10135 Torino (Italy)
3. IMEM-CNR, Parco Area delle Scienze, I-43010 Fontanini, Parma (Italy)

A set of ferromagnetic thin films and multilayers containing 3d metals (Fe, Co) in different amounts was prepared by rf sputtering. Each sample exhibits a specific magnetic and magnetoresistive behavior, as expected for materials having different saturation magnetizations, magnetic anisotropies, and surface-to-volume ratios. From room temperature down to about 10 K, the magnetoresistance is explained in terms of well-known mechanisms; at low fields, a negative magnetoresistance is measured. Between {approx}10 and 30 K, the zero-field electrical resistance appears to be dominated by electron-phonon scattering. At lower temperatures, where the R vs T curve is almost saturated, a sudden drop of the resistance appears, whose magnitude and position vary from sample to sample. Below the drop temperature, a region of positive magnetoresistance is systematically observed at around H=0 in measurements done with the magnetic field applied either parallel or perpendicular to the film plane. The dip magnitude increases with decreasing temperature. The anomaly appears to be related to the presence of magnetic inhomogeneity in the samples. The experimental results are not explained in terms of standard magnetoresistance mechanisms. Effects related to quantum coherence of conduction electrons may be the source of the observed anomalies. The role of weak localization of electrons, inhibited by the additional scattering provided by the magnetic inhomogeneity on the nanometer scale, is discussed.

• OSTI ID: 21137285
• Journal Information: Journal of Applied Physics, Vol. 103, Issue 7; Other Information: DOI: 10.1063/1.2901185; (c) 2008 American Institute of Physics; Country of input: International Atomic Energy Agency (IAEA); ISSN 0021-8979
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
ANISOTROPY
COBALT
CRYSTAL GROWTH
ELECTRONS
FERROMAGNETIC MATERIALS
IRON
MAGNETIC FIELDS
MAGNETIZATION
MAGNETORESISTANCE
PHONONS
SCATTERING
SPUTTERING
SURFACE COATING
TEMPERATURE DEPENDENCE
TEMPERATURE RANGE 0000-0013 K
TEMPERATURE RANGE 0013-0065 K
TEMPERATURE RANGE 0065-0273 K
TEMPERATURE RANGE 0273-0400 K
THIN FILMS