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<p class="MsoNormal" style="text-align: left; margin: 0cm 0cm 0pt; layout-grid-mode: char;" align="left"><span class="text"><span style="font-family: ";Arial";,";sans-serif";; font-size: 9pt;">Two effective attacks, namely de-synchronization attack and impersonation attack, against Ha et al.’s LCSS RFID authentication protocol, Song and Mitchell’s protocol are identified. The former attack can break the synchronization between the RFID reader and the tag in a single protocol run so that they can not authenticate each other in any following protocol run. The latter can impersonate a legal tag to spoof the RFID reader by extracting the ID of a specific tag during the authentication process. An impersonation attack against Chen et al.’s RFID authentication scheme is also identified. By sending malicious queries to the tag and collecting the response messages emitted by the tag, the attack allows an adversary to extract the secret information from the tag and further to impersonate the legal tag.</span></span><span style="font-family: ";Arial";,";sans-serif";; font-size: 9pt;"></span></p>

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Ferroelectric perovskite oxide materials for photovoltaics (PV) have received considerable attention for their switchable PV responses and above-bandgap photovoltages as a type of new-generation PV device. Relatively large bandgap and low photocurrent remain major problems for their PV applications. Herein, we report the PV response of ferroelectric double-perovskite Bi2FeMnO6 (BFMO) thin films. It was found that the photocurrent density (Jsc) of a Sn:In2O3 (ITO)/BFMO/SrRuO3 (SRO) thin film device is two orders of magnitude higher than that of BiFeO3, and its power conversion efficiency is about 430 times larger than that of BiFeO3 under AM 1.5G illumination. The built-in electric field near the BFMO/SRO interface, which represents the Schottky contact, leads to the separation of photon-generated carriers. More importantly, the electric poling treatment on the BFMO device can manipulate significantly the magnitude of Jsc, which is independent of the polarization direction. This electric-field modulated PV effect in the poled BFMO device originates from the modulation of the Schottky barrier height at the BFMO/SRO interface. The redistribution of oxygen vacancies after electric poling treatment is mainly responsible for the modulation of the Schottky barrier height.