Superparamagnetism in Si1 – xGex (B, Hf) Whiskers

Authors A. Druzhinin , I. Ostrovskii , Yu. Khoverko, N. Liakh-Kaguy

Lviv Polytechnic National University, 12, S. Bandera St., 29013 Lviv, Ukraine

Issue Volume 13, Year 2021, Number 6
Dates Received 06 September 2021; revised manuscript received 02 December 2021; published online 20 December 2021
Citation A. Druzhinin, I. Ostrovskii, Yu. Khoverko, N. Liakh-Kaguy, J. Nano- Electron. Phys. 13 No 6, 06019 (2021)
PACS Number(s) 72.20
Keywords Whiskers (3) , Silicon-germanium, Hafnium (3) , Magnetic susceptibility, Superparamagnetism.

The paper deals with studies of magnetization and magnetic susceptibility of Si1 – xGex <B, Hf> (x = 0.05) whiskers with a diameter of about 1 μm in the temperatures range 77-300 K and magnetic fields up to 4.28 kOe. The obtained results have showed that the whisker magnetic susceptibility differs substantially from the typical diamagnetic bulk material. The main difference is connected with the existence of paramagnetic centers localized in the nanoporous coating, the so-called core-shell structure, of Si1 – xGex whiskers. This leads to the emergence of magnetic ordering in them and appearance of a paramagnetic component in the magnetic susceptibility. An increase in the paramagnetic component was observed due to the introduction of Hf dopants as separate paramagnetic centers. The oxygen presence in the whisker core-shell structure was also found due to Auger spectroscopy associated with the VLS mechanism of the Si1 – xGex whisker growth. As a result, HfO2 clusters are formed as a bulk material typical of diamagnets. The field behavior of the magnetic susceptibility component has a superparamagnetic character, which is characteristic of superparamagnetism saturation of magnetization and hysteresis absence in the temperature range 77-300 K. Therefore, the observed phenomena are explained by the existence of dangling bonds, as well as HfO2 clusters, in the whisker nanoporous coating according to magnetic ordering and the superparamagnetism appearance in Si1 – xGex <B, Hf> whiskers.

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