Roland Höhne

Learn More
We provide evidence that proton irradiation of energy 2.25 MeV on highly oriented pyrolytic graphite samples triggers ferro- or ferrimagnetism. Measurements performed with a superconducting quantum interferometer device and magnetic force microscopy reveal that the magnetic ordering is stable at room temperature.
Elemental carbon represents a fundamental building block of matter and the possibility of ferromagnetic order in carbon has attracted widespread attention. However, the origin of magnetic order in such a light element is only poorly understood and has puzzled researchers. We present a spectromicroscopy study at room temperature of proton irradiated(More)
The discovery of nanostructured forms of molecular carbon has led to renewed interest in the varied properties of this element. Both graphite and C60 can be electron-doped by alkali metals to become superconducting; transition temperatures of up to 52 K have been attained by field-induced hole-doping of C60 (ref. 2). Recent experiments and theoretical(More)
Epitaxial magnetite thin films with (loo), (1 10) and (1 11) orientation have been deposited by Laser ablation onto substrates with [NaCI] and [Spinel] strudure. X-ray dif£raction revealed pseudomorphic growth for (100) and (11 1) oriented films on MgO (100) and ZnFe,04 (1 11) respectively, whereas films on M&04 showed a high degree of relaxation For films(More)
Because of the biological compatibility, light weight and low cost, the possibility of having a room temperature carbon-based metal-ion free magnet attracts currently the interest of the scientific community. The search for magnetic ordering in carbon-based materials started, however, more than 15 years ago as Makarova [1] recently reviewed in detail. First(More)
In order to study a possible magnetic proximity effect in magnetite-carbon structures, we have performed magnetization measurements of graphite-magnetite composites with different mass ratios as well as the measurement of the magnetoresistance of one of them and of the magnetization of a magnetite-carbon bilayer. The overall results do not indicate the(More)
m i t F e S bzw. F e N B i n d u n g e n auch IRspek t ro skop i sch b e o b a c h t e n lieBe. Die Autorei1 [3] waren yon der A n n a h m e ausgegangen , dab es s ich u m ein H e x a t h i o c y a n a t o f e r r a t ( I I I ) m i t F e S B i n d u n g e n halldele. I nzwi schen s t e h t jedoch fest , dab Fe(III) n u r ein H e x a i s o t h i o c y a n a(More)
  • 1