Complex physical properties of EuMgSi – a complementary study by neutron powder diffraction and 151Eu Mössbauer spectroscopy. Issue 27 (24th June 2015)

• Record Type: Journal Article
• Authors: Niehaus, O.; Ryan, D. H.; Flacau, R.; Lemoine, P.; Chernyshov, D.; Svitlyk, V.; Cuervo-Reyes, E.; Slabon, A.; Nesper, R.; Schellenberg, I.; Pöttgen, R.
• Is Part Of: Journal of materials chemistry. Volume 3:Issue 27(2015)
• Page Start: 7203
• Page End: 7215
• Publication Date: 2015-06-24
• Subjects: Materials -- Periodicals; Chemistry, Analytic -- Periodicals; Optical materials -- Research -- Periodicals; Electronics -- Materials -- Research -- Periodicals; 543.0284
• DOI: 10.1039/c5tc01017a
• Languages: English
• ISSNs: 2050-7526

Abstract

Abstract : X-ray pure samples of EuMgSi were synthesized by reactions of the elements in sealed niobium tubes using a high frequency and subsequently a resistance furnace. Abstract : X-ray pure samples of EuMgSi were synthesized by reactions of the elements in sealed niobium tubes using a high frequency and subsequently a resistance furnace. The structure was investigated by single crystal X-ray diffraction: TiNiSi-type, Pnma, a = 769.5(2), b = 455.0(1), c = 836.9(2) pm, w R 2 = 0.033 [ I ≥ 2 σ ( I )], and 705 F 2 values with 20 variables. Powder synchrotron radiation diffraction experiments did not reveal any structural changes down to 4.3 K. Magnetic susceptibility data and 151 Eu Mössbauer spectra clearly indicate a stable Eu 2+ configuration. Two distinct magnetic anomalies around 12 and 14 K can be observed for different samples with dc- and ac-susceptibility, heat capacity and resistivity measurements. Fitting of hyperfine field splitting as a function of temperature ( 151 Eu Mössbauer spectroscopy data) with a Brillouin function also leads to a magnetic ordering around 14 K. Electronic structure calculations in coincidence with the resistivity measurement prove narrow (or nearly zero) gap-semiconducting behaviour. The calculated band gap energy of 0.03 eV should be considered with precautions due to the accuracy of this method. An incommensurate magnetic structure with the propagation vector k = [ q x ≈ 0.37, 0, 0] was determined using neutron diffraction data at 5.5 K. In consensus of dc- and ac-susceptibility and neutron powder diffraction a complex combination of antiferromagnetic and ferromagnetic interactions, most likely by super-exchange, is confirmed. These cause two magnetic ordering temperatures, though only one independent crystallographic Eu site in terms of the crystal structure is present in EuMgSi.