Professor Lampl, a widely renowned composer previously of the Juilliard School in New York, joined the university in 2016. In October, he was accused by staff of plagiarising the new team song he composed for the Canberra Cavalry in 2017, due to its apparent similarities to the Go Cubs Go! anthem of US baseball team, the Chicago Cubs.

A university spokeswoman said an independent review had investigated the allegation the Go Cavs Go! song breached copyright law but cleared Professor Lampl "of any wrongdoing" in December.

"Professor Lampl’s decision to step down was his own," she said.

"The university is delighted to retain Professor Lampl’s exceptional vision, talent and wealth of composition experience as an academic and teacher."

Professor Lampl has composed music for more than 70 films, TV shows and video games.

He had described the Canberra Calvary song at the time as a unique collaboration between the baseball team and the university, drawing together traditional team songs and chants.

Since news of his resignation emerged on Thursday, Professor Lampl has emphasised that he left the top job to pursue other creative projects. That will include designing the course in film and video game composition he first came to the university to teach.

"While I am proud of my achievements as head of the school, the reason I came to the ANU was to build [this] program and to be a part of the growing film and video game industry in Australia as a professional composer," he said.

"I am particularly excited to be returning to my main passion and focus at ANU."

His resignation is just the latest episode in a troubled history for the institution, which spent 18 months searching for a new director after the controversial departure of Peter Tregear.

Professor Tregear was brought in in 2012 to run and restore confidence in the school after then vice-chancellor Ian Young instituted dramatic staff and budget cuts.

He left suddenly in August, 2015.

The school was without a director for the next 18 months, battling more instability and funding cuts.

In a statement on Monday, Professor Lampl maintained he had achieved much during his tenure, including radically turning around falling student enrolments and implementing new reforms at the school as part of the controversial Podger review.

The 2016 review, led by former public service commissioner Andrew Podger, found the school had been plagued by a legacy of distrust, emotional stress, years of poor management and sliding academic standards. It called for an overhaul of governance, staff culture and financial management.

Professor Lampl said under his direction enrolments had climbed by 148 per cent and the school had raised more than $200,000 for scholarships and student support, as well as forging new partnerships with business and industry.

But he said the workload as head of school was too great as his skills as a composer were also in demand.

"We teach by example and that can only happen by being an active practitioner of the art," he said.

"Composing for film and video games is an emerging and exciting career option in an industry that is growing exponentially. The ANU will lead the industry in delivering fresh new composers with the skills the industry needs."

One recommendation from the Podger review urged a head of school should be appointed “for a substantial fixed period to lead the change process”.

Distinguished musician Larry Sitsky, who was part of the panel advising Professor Podger, said that had “meant 10 years or more” and he hoped whoever now took up the role would provide stability for the school.

"Things at the school should have settled down more than they have since [it was] collapsing around us back then, but they have settled a certain amount," Professor Sitsky said.

"We need a captain to steady the ship."

A university spokeswoman said the head of school role, like all such roles across the university, were handed out for fixed terms of three to five years.

Professor Sitsky acknowledged the work of Professor Lampl in boosting student numbers again, but said the university now needed to turn its attention back to the original Podger review, which had included a "clear and a practical path forward".

"Most of what's in there still hasn't happened, especially around governance," he said.

The university said it was continuing to implement recommendations from the review and had invested $12.5 million into securing the long-term future of the school.

Professor Sitsky described last year's plagiarism allegations as embarrassing for the school.