INFLUENCE OF MAGNETIC STRUCTURE ON ELECTRIC CHARGE TRANSPORT IN THIN FILMS OF HOLMIUM AND DYSPROSIUM

Ján Dudáš – Viktor Kavečanský – Iwona Gosčiaňska – Stanislav Gabáni – Milan Guzan

   High precision electrical resistance measurements were performed on holmium and dysprosium bulk and thin film samples in a wide temperature range from 4.2 K up to the room temperature. Influence of magnetic structure on the resistance vs temperature (R vs T) curves was observed as a “knee-like” anomaly near the the Néel temperature value T_N = 128.9 K in Ho bulk sample and below 119. 5 K in Ho thin films. Numerical analysis of the R vs T data yielded the Curie temperature value TC = 19 K for Ho bulk sample. Unexpected resistance minimum at 9 K and a slope's change of the R vs T curve at ~ 170 K were observed in 215 nm thin Ho film. The X-ray diffraction of Ho films revealed diffraction peaks caused by the hcp structure of Ho and those from a holmium dihydrid. The bulk Dy sample showed a „hump-backed“ resistance anomaly near TN = 180.50 K and a sudden decrease of resistance value at TC = 92.00 K. A “knee-like” resistance anomaly below 179 K was observed in thinner dysprosium films, whereas a”hump-backed” one was observed in thicker films. The X-ray diffraction of Dy films in a thickness range from 25 nm to 350 nm showed peaks from the hcp structure of Dy and small peaks caused by dysprosium dihydrid.

Keywords: holmium, dysprosium, thin films, electrical resistivity, low temperatures, Néel temperature, Curie temperature, X-ray diffraction

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