The innovation engine for new materials

Madeline Shortt

Madeline Shortt, Physics, Mount Holyoke College

Major: 

Physics

University: 

Mount Holyoke College

Mentor(s): 

Moureen Kemei

Faculty Sponsor(s): 

Ram Seshadri

Faculty Sponsor's Department(s): 

Materials

Project Title: 

EVOLUTION OF MAGNETIC PROPERTIES IN THE PYROCHOLORES: Yb2+xTi2-xO7-x/2

Project Description: 

Strong ferromagnetic interactions compete with local spin anisotropy in the spin ice Yb2Ti2O7 yielding highly degenerate ground states where novel properties are predicted. Significant variations in the reported ground state properties of Yb2Ti2O7 show that this system is sensitive to stoichiometry. Here, we systematically investigated the effect of slight off-stoichiometry on the properties of Yb2Ti2O7 by examining the structural and magnetic properties of the system Yb2+xTi2-xO7-x/2, -0.1<x<0.1. We prepared crystalline samples of Yb2+xTi2-xO7-x/2. Synchrotron X-ray diffraction reveals a lattice expansion with increase in Yb3+ on Ti4+ sites. Concurrent with the lattice expansion, temperature-dependent magnetic susceptibility measurements show that antiferromagnetic interactions arise when excess Yb3+ populates Ti4+ sites. We demonstrate that adding excess Yb3+ in Ti4+ sites of Yb2Ti2O7 results in a lattice expansion as well as stronger antiferromagnetic behavior.