Acoustic wave device, radio-frequency front end circuit, and communication device

An acoustic wave device comprising:

• a piezoelectric body;
• an IDT electrode provided on the piezoelectric body;
• and
• a first dielectric film provided on the piezoelectric body and covering the IDT electrode;
• wherein
• the IDT electrode includes a first busbar and a second busbar that face each other, a plurality of first electrode fingers with first ends that are electrically connected to the first busbar, and a plurality of second electrode fingers with first ends that are electrically connected to the second busbar and that are interdigitated with the plurality of first electrode fingers,
• when an acoustic wave propagation direction is a first direction and a direction perpendicular or substantially perpendicular to the acoustic wave propagation direction is a second direction, the IDT electrode includes a crossing region that is a portion of the IDT electrode where the first electrode fingers and the second electrode fingers overlap in the first direction;
• the crossing region includes a center region located in a central portion of the first electrode fingers and the second electrode fingers in the second direction, a first edge region located outside the center region on the first busbar side in the second direction, and a second edge region located outside the center region on the second busbar side in the second direction,
• a first gap region is located outside the first edge region on the first busbar side in the second direction and a second gap region is located outside the second edge region on the second busbar side in the second direction;
• Love waves are utilized as acoustic waves;
• a mass-adding film is provided inside the first dielectric film in the first edge region and the second edge region;
• and
• when T1 is a film thickness of a portion of the first dielectric film located between the IDT electrode and the mass-adding film and T2 is a film thickness of a portion of the first dielectric film located between the mass-adding film and a surface of the first dielectric film on an opposite side from the piezoelectric body, T1/(T1+T2)<about 0.5.