Stress induced stripe formation in Pd/W(110)

Area of Science:

• Surface science and condensed matter physics.
• Materials science and thin film analysis.

Background:

• Submonolayer palladium (Pd) films on tungsten (W) surfaces exhibit complex phase behaviors.
• Understanding phase transitions is crucial for thin film growth and surface properties.

Purpose of the Study:

• To investigate the stress-induced stripe phase of submonolayer Pd on W(110).
• To elucidate the temperature-dependent mechanisms governing this phase.
• To characterize the transition from stripe phase to other surface structures.

Main Methods:

• Low-energy electron microscopy (LEEM) for direct observation of surface morphology.
• Low-energy electron diffraction (LEED) for analyzing surface structure and phase transitions.
• Thermodynamic modeling of boundary free energy and elastic relaxation.

Main Results:

• Observation of a stress-induced stripe phase in Pd/W(110) using LEEM.
• Temperature dependence explained by evolving boundary free energy and elastic relaxation with increasing boundary width.
• Stripe phase disordering occurs when correlation length matches the stripe period.
• Condensate to lattice-gas transition identified at higher temperatures via LEED.

Conclusions:

• The stripe phase is a distinct thermodynamic phase driven by surface stress.
• Boundary energy and elastic effects are key to the temperature dependence of the stripe phase.
• LEEM and LEED provide complementary insights into surface phase transitions in thin films.