Atomic-resolved depth profile of strain and cation intermixing around LaAlO 3 /SrTiO 3 interfaces

International audienceNovel behavior has been observed at the interface of LaAlO 3 /SrTiO 3 heterostructures such as two dimensional metallic conductivity, magnetic scattering and superconductivity. However, both the origins and quantification of such behavior have been complicated due to an interplay of mechanical, chemical and electronic factors. Here chemical and strain profiles near the interface of LaAlO 3 /SrTiO 3 heterostructures are correlated. Conductive and insulating samples have been processed, with thicknesses respectively above and below the commonly admitted conductivity threshold. The intermixing and structural distortions within the crystal lattice have been quantitatively measured near the interface with a depth resolution of unit cell size. A strong link between intermixing and structural distortions at such interfaces is highlighted: intermixing was more pronounced in the hetero-couple with conductive interface, whereas in-plane compressive strains extended deeper within the substrate of the hetero-couple with the insulating interface. This allows a better understanding of the interface local mechanisms leading to the conductivity

Role of the different defects, their population and distribution in the LaAlO3 /SrTiO3 heterostructure's behavior

International audienceHetero-interfaces between epitaxial LaAlO3 films and SrTiO3 substrates can exhibit an insulator-metal transition at a critical film thickness above which a quasi-two-dimensional electron gas forms. This work aims to elucidate the significant role the defects play in determining the sources of non-mobile and mobile carriers, the critical thickness, and the dipolar field screening. A model is built based on a comprehensive investigation of the origin of charge carriers and the advanced analysis of structural factors that affect the electronic properties of these hetero-epitaxial interfaces

Deciding Whether to Take Sacubitril/Valsartan: How Cardiologists and Patients Discuss Out‐of‐Pocket Costs

Background Out‐of‐pocket costs have significant implications for patients with heart failure and should ideally be incorporated into shared decision‐making for clinical care. High out‐of‐pocket cost is one potential reason for the slow uptake of newer guideline‐directed medical therapies for heart failure with reduced ejection fraction. This study aims to characterize patient–cardiologist discussions involving out‐of‐pocket costs associated with sacubitril/valsartan during the early postapproval period. Methods and Results We conducted content analysis on 222 deidentified transcripts of audio‐recorded outpatient encounters taking place between 2015 and 2018 in which cardiologists (n=16) and their patients discussed whether to initiate, continue, or discontinue sacubitril/valsartan. In the 222 included encounters, 100 (45%) contained discussions about cost. Cost was discussed in a variety of contexts: when sacubitril/valsartan was initiated, not initiated, continued, and discontinued. Of the 97 cost conversations analyzed, the majority involved isolated discussions about insurance coverage (64/97 encounters; 66%) and few addressed specific out‐of‐pocket costs or affordability (28/97 encounters; 29%). Discussion of free samples of sacubitril/valsartan was common (52/97 encounters; 54%), often with no discussion of a longer‐term plan for addressing cost. Conclusions Although cost conversations were somewhat common in patient–cardiologist encounters in which sacubitril/valsartan was discussed, these conversations were generally superficial, rarely addressing affordability or cost‐value judgments. Cardiologists frequently provided patients with a course of free sacubitril/valsartan samples without a plan to address the cost after the samples ran out