Kavli Affiliate: Herre S. J. Van Der Zant
| First 5 Authors: Raphaela de Oliveira, Raphaela de Oliveira, , ,
| Summary:
Biotite crystals are phyllosilicate trioctahedral micas with the general
chemical formula K(Mg,Fe)3AlSi3O10(OH)2 that form a solid-solution series with
iron-poor phlogopite and iron-rich annite endmembers. With a wide band gap
energy and a layered structure with free surface charges, biotite nanosheets
can be readily obtained by cleavage methods and used as dielectrics in
nanodevice fabrication for the next generation of electronics and energy
harvesting. Here, a comprehensive study of biotite samples with different iron
concentrations and oxidation states is presented. Structural, optical,
magneto-optical, and magnetic characterizations were performed using several
experimental techniques, including state-of-the-art synchrotron-based
techniques, to correlate the iron chemistry (content and oxidation state) with
the macroscopic properties of both minerals. The study reveals a
nanoscale-homogeneous Fe distribution via synchrotron X-ray fluorescence
mapping, defect-mediated optical transitions modulated by Fe3+/Fe2+ ratios, and
temperature-dependent magnetic transitions from paramagnetism to competing
ferro-/antiferromagnetic interactions. Furthermore, the use of these biotite
crystals as substrates for ultrathin heterostructures incorporating monolayer
(ML) MoSe2 is explored by magneto photoluminescence at cryogenic temperatures.
The results show that the presence of iron impurities in different oxidation
states significantly impacts the valley properties for ML-MoSe2. Overall, these
findings offer a comprehensive interpretation of the physical properties of
bulk biotites in a correlative approach, serving as a robust reference for
future studies aiming to explore biotites in their ultrathin form.
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