Synthesis and Characterization of Hf2Te2P
My work with the Experimental Condensed Matter Physics Research GroupThe Project
Hf2Te2P is a recently discovered topological material that is made using Vapor Transport Synthesis. My project was to look at the previous research on the structural analogue Zr2Te2P and derive a synthesis method for the material in a 3-zone furnace. Once the material was synthesized, I was to characterize the material for phase purity using XRD measurements and Rietveld refinement as well as scan for quantum oscillations using MPMS measurements. Once this material was characterized, I would give the single crystals of Hf2Te2P to the da Silva Neto group for STM and ARPES measurements of the material’s band structure.
The Results
Once the synthesis parameters were successfully controlled to consistently produce large crystals of Hf2Te2P, the largest crystals were measured for quantum oscillations to find a suitable crystal for further STM and ARPES measurements. These crystals were then measured using these machines, yielding a discovery in the Band Structure of Hf2Te2P which was published in Physical Review B. Shown below is (a) the Fourier transform of the STS map at 240mV. (b) Line cut of (a) along [Qx = 0, Qy], showing a distinct peak at
Qy = 0:09 (1/A° ). (c) QPI dispersion maps along the Γ-M and
Γ-K directions.
Experimental Methods
Based on the previous research of the Structural Analogue, many experimental syntheses were performed using various temperature gradients, tube lengths, airflow values, and cooling curves to find the optimal mass transfer rate and avoid the binary HfTe2 phase that was prevalent in early XRD scans of the Material. Shown above is the MPMS data that I had obtained on the sample that was analyzed in the publication. Note the large change in Magnetic Moment with small oscillations of Magnetic Field, these are the quantum oscillations we are looking for in the material. Shown below is a picture of a crystal from the batch used in this publication. I am not sure which exact crystal was probed for its band structure, but chances are it looked quite similar to this crystal!
