Catálogo de publicaciones - revistas

<jats:title>Engineering perovskites with anions</jats:title> <jats:p> The bandgap of the perovskite top layer in tandem silicon solar cells must be tuned to ∼1.7 electron volts. Usually, the cation composition is varied because the bromine-rich anion compositions with wide bandgaps are structurally unstable. Kim <jats:italic>et al.</jats:italic> show that by using phenethylammonium as a two-dimensional additive, along with iodine and thiocyanate, bromine-rich perovskite films can be stabilized. A tandem silicon cell delivered &gt;26% certified power conversion efficiency, and a perovskite device maintained 80% of its initial power conversion efficiency of &gt;20% after 1000 hours under illumination. </jats:p> <jats:p> <jats:italic>Science</jats:italic> , this issue p. <jats:related-article xmlns:xlink="http://www.w3.org/1999/xlink" ext-link-type="doi" issue="6487" page="155" related-article-type="in-this-issue" vol="368" xlink:href="10.1126/science.aba3433">155</jats:related-article> </jats:p>

<jats:title>A spin-pumping antiferromagnet</jats:title> <jats:p> Antiferromagnets have been used in spintronics mainly as a source of the so-called exchange bias. However, they hold promise for a much more active role given that their magnetization dynamics can in principle be much faster than those in ferromagnets. For this promise to materialize, antiferromagnets must learn the tricks that come naturally to ferromagnets. Vaidya <jats:italic>et al.</jats:italic> observed one such phenomenon called spin pumping (see the Perspective by Hoffmann). The researchers irradiated the antiferromagnet MnF <jats:sub>2</jats:sub> with circularly polarized subterahertz light, causing the spins in this material to spring into action. These dynamics, in turn, caused the injection of spin current into a layer of platinum adjacent to MnF <jats:sub>2</jats:sub> . </jats:p> <jats:p> <jats:italic>Science</jats:italic> , this issue p. <jats:related-article xmlns:xlink="http://www.w3.org/1999/xlink" ext-link-type="doi" issue="6487" page="160" related-article-type="in-this-issue" vol="368" xlink:href="10.1126/science.aaz4247">160</jats:related-article> ; see also p. <jats:related-article xmlns:xlink="http://www.w3.org/1999/xlink" ext-link-type="doi" issue="6487" page="135" related-article-type="in-this-issue" vol="368" xlink:href="10.1126/science.aba8388">135</jats:related-article> </jats:p>

<jats:title>Forest dynamics and demography</jats:title> <jats:p> Tropical forest succession has been viewed mostly by considering trees in categories of early-, mid-, and late-successional species, corresponding to a fast–slow continuum of life history strategies. Rüger <jats:italic>et al.</jats:italic> now show that the fast–slow continuum does not capture the demographic strategy of the long-lived pioneer species, an important component of many tropical forests (see the Perspective by Bugmann). They developed a forest model that allows for objective predictions of tropical forest dynamics and validated the model's predictions against independent data. These findings should advance our understanding of tropical forest dynamics and facilitate sustainable tropical forest management. </jats:p> <jats:p> <jats:italic>Science</jats:italic> , this issue p. <jats:related-article xmlns:xlink="http://www.w3.org/1999/xlink" ext-link-type="doi" issue="6487" page="165" related-article-type="in-this-issue" vol="368" xlink:href="10.1126/science.aaz4797">165</jats:related-article> ; see also p. <jats:related-article xmlns:xlink="http://www.w3.org/1999/xlink" ext-link-type="doi" issue="6487" page="128" related-article-type="in-this-issue" vol="368" xlink:href="10.1126/science.abb7020">128</jats:related-article> </jats:p>

<jats:title>High winds in an extrasolar atmosphere</jats:title> <jats:p> Brown dwarfs are objects intermediate in mass between large planets and small stars, and their atmospheres share many characteristics with gas giant planets. Wind speeds in Solar System gas giant atmospheres can be derived by comparing the planet's rotational periods in the infrared (tracing the upper atmosphere) and radio (tied to the interior). Allers <jats:italic>et al.</jats:italic> observed a nearby brown dwarf, 2MASS J10475385+2124234, and determined its infrared and radio periods. They derived an average wind speed of ∼650 meters per second in a west-to-east direction. This technique should also work for exoplanets. </jats:p> <jats:p> <jats:italic>Science</jats:italic> , this issue p. <jats:related-article xmlns:xlink="http://www.w3.org/1999/xlink" ext-link-type="doi" issue="6487" page="169" related-article-type="in-this-issue" vol="368" xlink:href="10.1126/science.aaz2856">169</jats:related-article> </jats:p>

<jats:title>Looking for intermediate statistics</jats:title> <jats:p> Elementary particles in three dimensions are either bosons or fermions, depending on their spin. In two dimensions, it is in principle possible to have particles that lie somewhere in between, but detecting the statistics of these so-called anyons directly is tricky. Bartolomei <jats:italic>et al.</jats:italic> built a collider of anyons in a two-dimensional electron gas of GaAs/AlGaAs (see the Perspective by Feldman). Two beams of anyons collided at a beam splitter and then exited the device at two outputs. The researchers studied the correlations of current fluctuations at the outputs, which revealed signatures of anyonic statistics. </jats:p> <jats:p> <jats:italic>Science</jats:italic> , this issue p. <jats:related-article xmlns:xlink="http://www.w3.org/1999/xlink" ext-link-type="doi" issue="6487" page="173" related-article-type="in-this-issue" vol="368" xlink:href="10.1126/science.aaz5601">173</jats:related-article> ; see also p. <jats:related-article xmlns:xlink="http://www.w3.org/1999/xlink" ext-link-type="doi" issue="6487" page="131" related-article-type="in-this-issue" vol="368" xlink:href="10.1126/science.abb3552">131</jats:related-article> </jats:p>