Title

Electron Scattering Measurements of La1-xSrxMnO3

Document Type

Poster

Event Website

https://source2022.sched.com/

Start Date

16-5-2022

End Date

16-5-2022

Keywords

Phase Transitions, Electrical Resistivity, Ferromagnetism

Abstract

Materials are complex systems, built from a lattice of ions and containing electrons. There are many different types of interactions between electrons or between electrons and the lattice that stem from their electrical charges, spins, and orbital angular momenta. For specific experimental conditions (temperatures, pressures, etc.), one particular interaction can dominate, causing the material to undergo a phase transition into an ordered state promoted by that interaction. Measurements of electrical resistance as a function of temperature (ERFT) on materials can detect phase transitions and offer insight into the underlying interaction(s) responsible for producing the ordered state. When a phase transition occurs, a rapid change in resistance results since there is more scattering in disordered states and less scattering in ordered states. To measure ERFT, a current of electrons is directed through a sample; measured electrical resistance values depend on electron scattering in the material. Electrons can scatter from: (1) impurities and defects, (2) other conduction electrons, (3) the lattice, and (4) magnetic moments. The system La1-xSrxMnO3 is interesting because the phase transition temperatures associated with the ordered ferromagnetic state depend sensitively on the lanthanum to strontium ratio. To investigate these phase transitions, ERFT measurements were made between 4.2 - 300 kelvin on polycrystalline samples of La1-xSrxMnO3 from 0.1 ≤ x ≤ 0.3. Measurements were performed using a standard four-wire technique and a closed-cycle refrigerator to cool the samples. The results of these experiments demonstrate how sensitively ERFT measurements probe changes in electron scattering during a ferromagnetic phase transition.

Faculty Mentor(s)

Benjamin White

Department/Program

Physics

Additional Mentoring Department

Physics

Additional Files

McCrae, Nyal SOURCE Presentation.pptx (3471 kB)
Slides

McCrae, Nyal Source Presentation 2022.mp4 (17050 kB)
Video Presentation

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May 16th, 12:00 AM May 16th, 12:00 AM

Electron Scattering Measurements of La1-xSrxMnO3

Materials are complex systems, built from a lattice of ions and containing electrons. There are many different types of interactions between electrons or between electrons and the lattice that stem from their electrical charges, spins, and orbital angular momenta. For specific experimental conditions (temperatures, pressures, etc.), one particular interaction can dominate, causing the material to undergo a phase transition into an ordered state promoted by that interaction. Measurements of electrical resistance as a function of temperature (ERFT) on materials can detect phase transitions and offer insight into the underlying interaction(s) responsible for producing the ordered state. When a phase transition occurs, a rapid change in resistance results since there is more scattering in disordered states and less scattering in ordered states. To measure ERFT, a current of electrons is directed through a sample; measured electrical resistance values depend on electron scattering in the material. Electrons can scatter from: (1) impurities and defects, (2) other conduction electrons, (3) the lattice, and (4) magnetic moments. The system La1-xSrxMnO3 is interesting because the phase transition temperatures associated with the ordered ferromagnetic state depend sensitively on the lanthanum to strontium ratio. To investigate these phase transitions, ERFT measurements were made between 4.2 - 300 kelvin on polycrystalline samples of La1-xSrxMnO3 from 0.1 ≤ x ≤ 0.3. Measurements were performed using a standard four-wire technique and a closed-cycle refrigerator to cool the samples. The results of these experiments demonstrate how sensitively ERFT measurements probe changes in electron scattering during a ferromagnetic phase transition.

https://digitalcommons.cwu.edu/source/2022/COTS/73