Ferroelectric switching and temperature-dependent electrical properties of <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:mrow> <mml:msub> <mml:mi mathvariant="normal">K</mml:mi> <mml:mrow> <mml:mn>0.7</mml:mn> </mml:mrow> </mml:msub>

We performed the macroscopic electrical characterization of epitaxially grown, compressively strained <a:math xmlns:a="http://www.w3.org/1998/Math/MathML"> <a:mrow> <a:msub> <a:mi mathvariant="normal">K</a:mi> <a:mrow> <a:mn>0.7</a:mn> </a:mrow> </a:msub> <a:msub> <a:mi>Na</a:mi> <a:mrow> <a:mn>0.3</a:mn> </a:mrow> </a:msub> <a:msub> <a:mi>NbO</a:mi> <a:mn>3</a:mn> </a:msub> </a:mrow> </a:math> thin films (70 nm) on <c:math xmlns:c="http://www.w3.org/1998/Math/MathML"> <c:mrow> <c:msub> <c:mi>SrRuO</c:mi> <c:mn>3</c:mn> </c:msub> <c:mo>/</c:mo> <c:mrow> <c:mo>(</c:mo> <c:mn>110</c:mn> <c:mo>)</c:mo> </c:mrow> <c:msub> <c:mi>TbScO</c:mi> <c:mn>3</c:mn> </c:msub> </c:mrow> </c:math> substrates, displaying monoclinic <d:math xmlns:d="http://www.w3.org/1998/Math/MathML"> <d:mrow> <d:mi mathvariant="italic">Mc</d:mi> </d:mrow> </d:math> domains. Hysteresis measurements revealed ferroelectric behavior up to at least <f:math xmlns:f="http://www.w3.org/1998/Math/MathML"> <f:msup> <f:mn>10</f:mn> <f:mn>7</f:mn> </f:msup> </f:math> cycles at room temperature, with a polarization value ( <g:math xmlns:g="http://www.w3.org/1998/Math/MathML"> <g:mrow> <g:mn>2</g:mn> <g:mi>P</g:mi> </g:mrow> </g:math> ) of <h:math xmlns:h="http://www.w3.org/1998/Math/MathML"> <h:mrow> <h:mn>25</h:mn> <h:mspace width="0.16em"/> <h:mi>µ</h:mi> <h:mi mathvariant="normal">C</h:mi> <h:mo>/</h:mo> <h:msup> <h:mrow> <h:mi>cm</h:mi> </h:mrow> <h:mn>2</h:mn> </h:msup> </h:mrow> </h:math> . A double-peak switching behavior was observed, attributed primarily to domain-wall pinning/depinning and back switching, with a wake-up effect analogous to that reported in doped hafnium oxide and lead zirconate titanate systems. Temperature-dependent measurements (100 K—300 K) confirm ferroelectricity at low temperatures, while the double-peak behavior becomes less pronounced due to suppression of thermally activated back switching. Capacitance-voltage measurements reveal an increased dielectric response at higher temperatures, consistent with enhanced domain wall mobility. The asymmetry in coercive voltages additionally points to internal bias fields likely arising from electrode interfaces. Our results provide a comprehensive overview of the switching dynamics of strained <k:math xmlns:k="http://www.w3.org/1998/Math/MathML"> <k:mrow> <k:msub> <k:mi mathvariant="normal">K</k:mi> <k:mrow> <k:mn>0.7</k:mn> </k:mrow> </k:msub> <k:msub> <k:mi>Na</k:mi> <k:mrow> <k:mn>0.3</k:mn> </k:mrow> </k:msub> <k:msub> <k:mi>NbO</k:mi> <k:mn>3</k:mn> </k:msub> </k:mrow> </k:math> films and demonstrate ferroelectricity in the <m:math xmlns:m="http://www.w3.org/1998/Math/MathML"> <m:mrow> <m:mi mathvariant="italic">Mc</m:mi> </m:mrow> </m:math> phase.