Cracking the Pressure Code: How 2D Materials Reveal Their Secrets Under Stress

2D MoS2 under Pressure

Published in: Nature Communications (2025)

Imagine squeezing a stack of molecular paper—layer by atomic layer—and watching it whisper back secrets of its internal structure. This is no longer just the stuff of science fiction. In an exciting new study, researchers from several leading Chinese institutions have leveraged ultralow-frequency (ULF) Raman spectroscopy to probe the internal mechanics of layered nanomaterials like molybdenum disulfide (MoS2)—a flagship material in the realm of two-dimensional (2D) materials science.

The Pressure Paradigm in 2D Nanomaterials

Two-dimensional materials like MoS2, graphene, and their van der Waals cousins are stacked with weak interlayer forces that play a crucial role in their electronic, mechanical, and optical behaviors. But until now, accurately quantifying these interlayer forces under pressure—and understanding their implications for device performance—has proven elusive.

This new study fills that gap. By carefully applying hydrostatic pressure using a diamond anvil cell and measuring subtle Raman shifts in phonon vibrations, the research team was able to precisely map how these materials respond under stress. Their model materials were MoS2 nanoflakes of varying thickness, ranging from two to nine layers, and even bulk samples.

Layered Dynamics: More Than Just Stacking

One of the study's standout findings is the opposite pressure-response behavior of two key vibrational modes—shear modes (S) and layer-breathing modes (LB). These are sensitive to both the number of layers and the strength of interlayer coupling. Surprisingly, the pressure-induced frequency shift (dω/dP) of these modes shows contrasting trends with layer number: the shear mode’s shift rate increases while the LB mode’s decreases as the material gets thicker.

This effect is elegantly modeled using the Monoatomic Chain Model (MCM), which interprets each atomic layer as a “mass” connected by springs (interlayer forces). The study’s use of both density functional theory (DFT) and molecular dynamics (MD) simulations confirmed the experimental trends, showcasing excellent consistency across theory and observation.

Elasticity Enhanced: Moduli on the Rise

The researchers also calculated key elastic constants—C33 and C44—that correspond to out-of-plane and in-plane stiffness, respectively. Under pressure up to 9.6 GPa, these constants increased significantly, especially for the interlayer C33, implying a tunable mechanical robustness in 2D materials. Notably, even under high pressure, the interlayer interactions remained weak enough to retain the “2D character” of MoS2.

Applications and Beyond

Why does this matter? As flexible electronics, pressure-sensitive sensors, and “twistronics” devices come closer to real-world deployment, the ability to modulate and predict the mechanical response of layered materials becomes mission-critical. This research lays the groundwork for pressure-engineered 2D devices with tailored properties for nanoelectronics, optoelectronics, and straintronic applications.

What's Next?

This study doesn’t stop at MoS2. The methodology—ULF Raman spectroscopy combined with MCM and DFT analysis—can be applied to other van der Waals materials like MoTe2, WSe2, and even twisted bilayer structures where moiré patterns govern electronic phases.

The article concludes with a promise: by decoding pressure-induced changes in vibrational properties, scientists can design smarter, more adaptable 2D materials. It’s a major step forward in understanding the nanoscale mechanics of tomorrow’s quantum materials.

🔗 Full Article:

https://www.nature.com/articles/s41467-025-60211-8

Originally reported by: Guoshuai Du, Lili Zhao, Shuchang Li, et al. at Beijing Institute of Technology, Tsinghua University, and Nanjing University.

#QuantumMaterials #2DMaterials #MoS2 #Nanomechanics #RamanSpectroscopy #VanDerWaals #HighPressurePhysics #Nanoelectronics #MaterialsScience #Twistronics

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