Magnetic properties of graphite irradiated with MeV ions

Journal Article · Tue Jun 01 00:00:00 EDT 2010 · Physical Review. B, Condensed Matter and Materials Physics

DOI:https://doi.org/10.1103/PHYSREVB.81.214404· OSTI ID:21386736

Ramos, M A; Munoz-Martin, A; Climent-Font, A ^[1]; Barzola-Quiquia, J; Esquinazi, P ^[2]; Garcia-Hernandez, M ^[3]

---

1. CMAM and Instituto de Ciencia de Materiales 'Nicolas Cabrera', Universidad Autonoma de Madrid, Cantoblanco, E-28049 Madrid (Spain)
2. Division of Superconductivity and Magnetism, Institut fuer Experimentelle Physik II, Universitaet Leipzig, Linnestrasse 5, D-04103 Leipzig (Germany)
3. Instituto de Ciencia de Materiales de Madrid, CSIC, Cantoblanco, E-28049 Madrid (Spain)

We have studied the change in the magnetic properties produced on highly oriented pyrolytic graphite samples by irradiation of H, C, and N ions in the mega-electron-volt energy range. The use of specially made sample holders for the magnetic measurements provided high reproducibility allowing us to obtain directly the irradiation effects without any corrections or subtractions. Our results show that three magnetic phenomena are triggered by the defects produced by the irradiation, namely, Curie-type paramagnetism, ferromagnetism and an anomalous paramagnetic state that appears as precursor of the magnetic ordered state. Using SRIM simulations to estimate the amount of vacancies produced by the irradiation, the Curie-type paramagnetic response indicates an effective Bohr magneton number per nominally produced vacancy p=0.27+-0.02mu{sub B}. Direct measurements of the surface sample temperature during irradiation and the decrease in the (as-received) paramagnetic as well as ferromagnetic contributions after irradiation indicate that self-heating is one of the causes for small yield of ferromagnetism. Taking into account the hydrogen distribution in the virgin samples, the obtained results indicate that the induced ferromagnetism appears when the average vacancy distance is {approx}2 nm in the near surface region.

• OSTI ID: 21386736
• Journal Information: Physical Review. B, Condensed Matter and Materials Physics, Vol. 81, Issue 21; Other Information: DOI: 10.1103/PhysRevB.81.214404; (c) 2010 The American Physical Society; ISSN 1098-0121
• Country of Publication: United States
• Language: English

Related Subjects

75 CONDENSED MATTER PHYSICS
SUPERCONDUCTIVITY AND SUPERFLUIDITY
CORRECTIONS
CRYSTAL DEFECTS
DISTANCE
DISTRIBUTION
ELECTRONS
FERROMAGNETISM
GRAPHITE
HEATING
HYDROGEN
IRRADIATION
MAGNETIC PROPERTIES
MEV RANGE
NITROGEN IONS
PARAMAGNETISM
PRECURSOR
SAMPLE HOLDERS
SIMULATION
SURFACES
CARBON
CHARGED PARTICLES
CRYSTAL STRUCTURE
ELEMENTARY PARTICLES
ELEMENTS
ENERGY RANGE
FERMIONS
IONS
LEPTONS
MAGNETISM
MINERALS
NONMETALS
PHYSICAL PROPERTIES