We will host monthly early-career seminars to provide a friendly, supportive platform for young researchers to showcase and communicate their research in English and to expand their professional networks by connecting with researchers in Japan and abroad. 

We are pleased to announce the third seminar.

Speaker：Dr. Tessa Cookmeyer  
Affiliation：University of California, Santa Barbara/KITP
Title：Triangular lattice magnets: hidden order and dimer criticality
Date and Time： April 3, 2026　11:00 - noon　Online only
Zoom：https://us02web.zoom.us/j/87426990484?pwd=5GmyKbKJj7kRReO80GKJ2CbPBaJkL0.1
Meeting ID: 874 2699 0484
Passcode: 802033

Abstract:
The triangular lattice, with its geometric frustration, has always been of particular interest in quantum magnets. In this talk, I will discuss recent experiments on two triangular-lattice quantum magnets, TmZn2GaO5 and K2Co(SeO)2, and our theoretical work surrounding them. I’ll argue that TmZn2GaO5, despite lacking magnetic Bragg peaks, exhibits a quadrupolar “order” with well-defined and measurable magnons. With its sister compound TmMgGaO4, it straddles a phase transition seen in the transverse-field Ising model on the triangular lattice. The second compound, K2Co(SeO)2, appears to enter a supersolid phase at low-temperatures, but we instead focus on the intermediate temperature region. We propose that its experimental features may be captured from a quantum dimer model and may be inside the critical fan of the Roksahr-Kivelson critical point.